Axinite

- Added `state` method

- Fixed load function problem with carriage return
- Automatic type checking in bodies
- `timestep` method
- Updated all docstrings
- Added better verbosity for axtools loading
- Speed up data saving a bit
- Bug fixes for backend errors when handling outer bodies

- Fixed live mode problems
- Fixed VPython errors with inner bodies
- Roughly removed AstroPY
- Added inner and outer bodies to decrease overhead

- Fixed error in `axtools.load`'s default action method
- Fixed some `combine` method indent problems