Big changes
Big changes

- Got rid of best backup state
- Reordered a simulation step to avoid projecting right before finishing
- Keep the lowest recorded variance ever to see the potential improvement if it weren't for truncation
- Changes to openmp threading
- Added threading options to input file
- Changed how many sites are selected before each xDMRG step


Former-commit-id: 2a8b07e6fae19537e8554d70f9a5d5c51bac67bb
DavidAce/DMRG,DavidAce/DMRG,DavidAce/DMRG,DavidAce/DMRG