Gsb

This release will mark the completion of the "Steel Thread" pre-MVP release of `gsb`, where barebones implementations of the most essential pieces of functionality are in place, namely:
- onboarding a savegame to `gsb` via `gsb init`
- creating a backup via `gsb backup`
- viewing a list of backups via `gsb history`
- restoring a backup via `gsb rewind`

What's Changed
* Initial CLI implementation by OpenBagTwo in https://github.com/OpenBagTwo/gsb/pull/22
* The CLI displays information now! by OpenBagTwo in https://github.com/OpenBagTwo/gsb/pull/23
* Implement CLI for gsb rewind by OpenBagTwo in https://github.com/OpenBagTwo/gsb/pull/24


**Full Changelog**: https://github.com/OpenBagTwo/gsb/compare/v0.0.1...v0.0.2-rc1

This release consists of Python implementation for the essential functionality of `gsb`:

- 16 implemented `onboard.create_repo`, which creates a new Git repo (or `gsb`-ifies an existing one) (1)
- 19 implemented `backup.create_backup`, which creates a new backup and, optionally, tags it for easy reference (3)
- 17 implemented `history.get_history`, which returns the available backup points (4)
- 20 implemented `rewind.restore_backup`, which does what it says on the tin while keeping the history linear and making it possible to restore to the post-restored-backup state (5)

Note that at this point there is no command-line interface.