Keyboard

- Added LICENSE.txt file to PyPI packages.
- Fixed typos in docstrings.
- Merged 281 and 259 (thanks luizeldorado and schldwcht !).

- [All] Improve release process, fixing 233 and 269.

- [Windows] Fix overflow error on Python 3.7.
- [Mac] Added alt gr -> alt mapping.
- [Mac] Added support for right shift.
- [All] Fixed numlock alias.
- [All] Fixed example code.

- [Mac] Fixed "map_name" error (i.e. implement new backend API).
- [Win] Improve detection of "right alt" key.
- [All] Misc fixes for edge cases.

- [Windows/Linux] Fixed installation.

- [All] New `remap_` and `block_` functions.
- [All] New high-level functions for parsing and converting hotkey names.
- [All] Added `.modifiers` and `.is_keymap` attribute to events.
- [All] Event name now matches character typed (e.g. now event from key `1` reports as `!` if shift is pressed). This gives `get_typed_strings` more precision.
- [Windows] New key suppression system should fix most bugs with `suppress=True`.
- [Linux] Added `.device` attribute to events.
- [All] Many, many bugfixes.