V3 compatible, Recalc improved, progress bars fixed

[mortii]

• Now works on the V3 scheduler (fixes 2021 (v3) scheduler support #276)
• Exponentially faster recalc action
• Progress dialogs are now shown when recalcing and anki no longer freezes (background thread is used instead of main thread)
• Renamed some files that were poorly named
• Refactored init file and extracted hidden hooks to make the code execution logic much clearer
• Added some type hints for clearer logic
• refactored some variable names to follow PEP conventions

[landonepps]

Overall looks good, I appreciate the attention to detail like renaming variables.
I'm happy to merge it if you can address the linter warnings.

Also, the master branch is outdated. The latest version on AnkiWeb is using the qt6-migration branch. I'll merge your changes into that branch after it gets merged to master.

[mortii]

I fixed the lint errors and I rebased onto qt6-migration

[mortii]

hold on, a very a sneaky error appeared that needs to be fixed

[mortii]

there was an invisible input parameter after removing a lambda, but it's fixed now.

[mortii]

Also this should probably be placed in the ankiweb description until we get a proper wiki/guide (next on my todo-lis):

NB! If the deck you are studying has sub-decks then new cards will by default only be gathered from the first sub-deck until it is empty before looking for new cards in the next sub-deck. If you instead want to get new i+1 cards from all sub-decks do the following:

1. Activate the v3 scheduler: Tools -> Review -> Scheduler -> V3 scheduler
2. Deck that has sub-decks: Deck options -> Display Order -> New card gather order -> Ascending position

The writing is kinda clunky, feel free to improve it in whatever way you see fit , lol.

[landonepps]

Looks good to me, thanks for all the work you did here.
And I appreciate the AnkiWeb note, I'll be sure to add it.

[PrentissLiu]

Thank you so much for your work. I am the version of QT5. I tried to modify:
readability_ui.py and readability_settings_ui.py :

from PyQt6 import QtCore, QtGui, QtWidgets

to:

from PyQt5 import QtCore, QtGui, QtWidgets

it works!

[landonepps]

Awesome, I really appreciate the report!
Both of my computers are arm-based Macs, which don't support Qt5, making it quite annoying to test.

If this is really all that's needed, I should be able to modify the UI generation code to replace these imports with the aqt version and have full backwards compatibility.