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* major changes under the hood.
- Now using `mt_metadata` to read/write transfer function files
- Now using `mth5` to store the transfer functions
- Introduced `MT`, `MTCollection`, and `MTData` such that operations are more centralized. Now most methods can be called from `MT` and `MTData`
- Removing older modules and group specific modules
- Added GitActions for testing
- Updating tests (still lots of work to do)
- Updated documentation to upload to ReadTheDocs