Canvascli

Added
- canvascli is now on PyPI!
- More readable visualizations.

Added
- Round grades to integers.
- Cap grades at 100.
- Optional overrides of detected course info.

Changed
- Abbreviate options flags.

Fixed
- Raise useful message upon unauthorized course access.

Added
- `show_courses` got a `--filter` option to facilitate finding the right course.
- `canvascli` now has a `--version` flag.
- Shell completion.

Changed
- The package was refactored to modularize functionality into subcommands, each with its own options.
- `dataclassy` is being used instead of `dataclasses` from `stdlib` in order to handle class inheritance with default values.

Initial release.