- first test of a GitHub CI for testing

- fixed wrong pip install and python versions in CI ?

- fixed loading of test files that do not contain test but dependencies that cannot be loaded ?

- escaped imports of unaccessible dependencies for test-file generation in GitHub CI tests by making the `if __name__ == "__main__"` include these imports and function definitions

- test whether Cython build can be removed from GitHub actions for testing ?

- reverted removal of Cython for testing

- moved the full package back into an `src`-folder

BLD:
- updated `pyproject.toml` and `setup.py` to account for the movement to the `src`-folder
- removed dedicated Cython build from CI test pipeline

- changed CI pipeline target branches

- augmented CI checks with format, type, and lint checks

- fixed CI pipeline wrong folder include ?

BLD:
- added isort check

- fixed broken `isort` usage in CI?

- fixed missing `isort` dependency in CI?
- fixed wrong import sort order in Cython Hermite functions

- fixed missing `colorama` dependency for `isort` in CI ?

- type-ignored Cython import that was not properly resolved by `pyright` ?

- fixed missing import of Cython module for `pyright`  in CI ?

- again trying to resolve the wrong import error of Cython module by `pyright` in CI ?

- fixed wrong `pyright` Cython import error of Cython import in CI

- removed pushes to `develop` from the GitHub CI actions

- added missing comma to the name of the GitHub CI action

* DOC:
- added Python versions and `black` code style to `README`

* DOC:
- added `isort` badge to `README`

* TST:
- added `--no-jit`-flag to `pytest` to enable proper coverage of Numba functions

* tmp:
- first test of CI with coverage report ?

* BUG:
- fixed failure of `pytest-xdist` and `pytest-cov` in GitHub CI (works locally) ?

* BUG:
- fixed accidentally placed `\` for `./tests` in coverage CI action ?

* BUG:
- added codecov to CI pipeline ?

* TST:
- tried to readd `pytest-xdist` for coverage reports ?

* wip:
- reset example Jupyter notebook number 3

* MAINT:
- made `_get_num_workers` a function of the `_utils`-model

TST:
- increased coverage to 100% by testing `np.float32` x-values for the Hermite functions was well as super negative numbers of requested workers

* DOC:
- added setup, installation, and development instructions to `README`

* DOC:
- switched back from `README.rst` to `README.md`

BLD:
- made CI pipeline push actions apply to the main branch only

- added `mypy` to CI pipeline

BUG:
- fixed type error that `mypy` uncovered for the `filename_parameters_mapping` for the Hermite function reference generation

- test if CI can still pass ?

- CI apparently still runs; removed check

- added `pycodestyle` as a part of the CI checks

BUG:
- fixed a line too long error revealed by `pycodestyle`

- added CI test status to `README` ?

- added functions that help for computing discrete/continuous Fourier transforms (`fourier_transform._fft_utils`)

TST:
- implemented a test suite for `fourier_transform._fft_utils`

DOC:
- updated equations with new definitions of $\alpha$
- updated `README` with new equations and added respective reference that these definitions are based on

MAINT:
- removed redundant Numba version of the legacy Hermite functions and `jit`-compiled the NumPy-version instead
- fixed minor documentation issues

MAINT:
- adapted interface to Hermite functions to the new definition of $\alpha$ in terms of both implementation and docs

DOC:
- updated example scripts and resulting plots with new definition of $\alpha$

TST:
- generated new references files for testing the new definition of $\alpha$ for the Hermite functions
- adapted Hermite function tests to properly run for the new definition of $\alpha$
- configured Hermite function tests via global constants and kept comments in them more vague
- made test for Cramér's inequality of the Hermite functions ensure that the boundary value is not only an upper bound but actually reached
- changed `requirements` for GitHub CI because with a re-arrangement of the `if __name__ == "__main__"` in the Hermite function reference generation file, `sympy` and `tqdm` became CI requirements as well

- fixed failing `ruff` for too long line in docstring of new `_fft_utils`

BLD:
- temporarily enabled CI on push to current branch to check if it still passes after an adaption in `pyright`

BLD:
- disabled GitHub CI on push to the current branch again after verifying that it still runs

ENH:
- added `x_center` to the Hermite function basis for shifting the Hermite functions in x-direction
- added input validation for `x_center`

MAINT:
- renamed `hermite_functions._interface` to `hermite_functions._func_interface` to prepare for the class interface
- made type handling of Hermite function input validation smarter and safer by first converting to the target type and then testing only for this one
- made argument types for `x` of the Hermite functions broader by also including lists and tuples

TST:
- made input validation tests for Hermite functions be executed before the Hermite function reference tests
- made input validation tests for Hermite functions not only check failure but also success cases
- added tests for the new `x_center` and ensured that it does not modify the original `x`-values for the Hermite functions (after this causes some problems)

DOC:
- updated all equations and the `README` to clarify the new `x_center` for the Hermite functions
- updated installation commands (also mentioned venv activation) and test/check commands in `README`

- added y-axis to Hermite-function-scale-effect-plot
- fixed first vertical x-axis for order `n=0` not showing in the plot at all

MAINT:
- moved Hermite function input validation to dedicated file

ENH:
- pushed forgotten files that add `x_center` to Hermite functions

TST:
- pushed forgotten files that test the new `x_center` of the Hermite functions and improved the testing of the Hermite function input validation

- split up tests for Hermite functions into dedicated test files to be more flexible

DOC:
- added common matplotlib style to unify all plots
- updated example scripts with new matplotlib style
- added shifted center to Hermite function example 01

- made example plots 01 and 02 for Hermite functions more visually appealing/less overwhelming

ENH:
- added auxiliary script that auto-generates a Python file with spline coefficients for almost exactly evaluating the largest zero (= outermost roots) of the Hermite functions up to order ~100_000

MAINT:
- refactored the reference creation for the largest roots of the Hermite functions to not minimize the relative but the absolute error
- relaxed permitted absolute error in reference creation for the largest roots of the Hermite functions because the SciPy-reference is not that accurate

DOC:
- mentioned that the SciPy-reference for the largest roots of the Hermite functions is not perfectly accurate

ENH:
- added script to create reference data for the largest extrema of the Hermite functions
- added new `_approximations`-module for Hermite functions that offers approximations for their largest roots, largest extrema, and fadeout points

TST:
- added tests for the new `_approximations`-module

DOC:
- added legend to first plot in script that creates reference data for the largest roots of the Hermite functions

- refactored the reference data generation for the largest roots and extrema of the Hermite functions to fit the splines based on relative errors
- updated reference data and plots created by these scripts
- made this reference data generation a developer-only script

TST:
- made test for largest root of Hermite functions more meaningful by adapting the tolerance for checking to the actual magnitude of the root position
- made test for largest extremum of Hermite functions more meaningful by checking the y-values (and not the x-values) of the extremum against a numerical optimisation (also with magnitude-adaptive tolerances)

- made all plot saves in examples available for developers only
- aligned plots in terms of visuals (especially titles and sizes)
- updated `README` with new plots and developer-only environment variable

- added additional scripts checks to GitHub CI
- made all tools cause actual failures rather than just printing test output ?
- broke CI on purpose, by badly formatting `auxiliary_scripts\02_hermite_functions_largest_extremum.py` and `src\robust_hermite_ft\hermite_functions\_c_hermite.pyx`

- CI tests fixed `black` formatting after confirming that it works
- `isort` is the next to check

- fixed `isort` CI failure after confirming that it works
- `pyright` is the next to check

- temporarily broke `isort` CI check again to check its output

- fixed `isort` problem again
- checking for reasons why `pyright`-check fails by running it separately without output ?

- fixed `pyright` error handling in CI
- `mypy` is the next one to check, but for now it's checked whether it just runs through even though there is an error

- pushing updated CI workflow file for properly testing that `mypy` just runs through
- added `matplotlib` to CI requirements to avoid `pyright` from throwing an error ?

- going back to the start for tests after `mypy` also stopped CI correctly
- starting with `black` test

- `black` successfully stopped the CI without customised handling
- `isort` is the next to check without customised handling

- also `isort` stops the CI on failure
- next to check is `pyright`

- reverted GitHub CI to its original working state

- updated `README` with new CI commands

- Hermite functions now support all kinds of real numeric scalars/Arrays as `x`-values, integer scalars as `n`-values, and real numeric scalars for `alpha` and `x_center` after making the input validation way more relaxed and smarter

TST:
- test for Hermite function input validation now covers Python and Numpy scalars individually and on top of that also includes Pandas series and Python Arrays
- test for data link to original `x` in Hermite functions now evaluates dynamically whether memory is shared by checking if changes in the copy/view are reflected in the original
- added a completely new test set whether the Hermite functions yield the same results for all different kinds of `x`-values, `n`-values, `alpha`- and `x-center` values

- fixed missing `pandas` dependency for GitHub CI

- fixed type incompatibility that caused `mypy` to crash the GitHub CI

- fixed missing coverage for default and error handling of FFT utility functions

- arranged legend of plot for special points of Hermite functions in a better position

- removed unnecessary list parametrization for orthonormality test of Hermite functions