Riscof

Changed
- Changed the command line args to use subparsers and added relevant documentation.

Fixed
- Migrated C-extension tests to those available on github. This required adding and fixing special
macros
- C.SWSP test has been fixed to not access regions outside the signature region
- Moved ECALL, EBREAK and MIS-ALIGNED tests to a separate folder. Also their respective TEST_CASE
conditions have been updated
- Moved Atomic tests to wip folder.
- renamed I-IO.S to I-IO-01.S

Fixed
- load_yaml function in utils forced to return dict type.

Fixed
- moved requirements.txt inside riscof

Fixed
- Removed duplicate env folder.
- Fixed exclusion of env folder in pip package.
- Reduced python package dependencies

Fixed
- shipping the model folder as well