Add DMRG-CASSCF, DMRG-NEVPT2 via PySCF

Merge pull request #24 from sunqm/master

Add documents and exampels for: DMRG-NEVPT2, DMRG-CASSCF via PySCF

v1.0.1 released with bug fixing

This minor version update contains bug fixes. Main changes are:

1.fixed mpi runtime error; processors now write intermediates files into different directories under scratch;
2.now printing summed cpu timings from all processors;
3.fixed error of orbital reordering in restart_npdm;
4.removed bugs in PT calculations;
5.test reference data now cleaned and consistent.

v1.0.0

The new release of v1.0.0 contains both bug fixes, improvments and new features, such as getting your warm-up step much faster, npdm up to fourth-order as well as transition pdm up to second-order, and perturbation methods, etc. Details about how to use them are available in the manual.