Changelog:
===========
- Renamed 'mask' variable in ABNF to prevent name collision with 'mask()' function
- Fixed old http import of HTTPStatus in _handshake.py
- Add 'send_text()' and 'send_bytes()' to _app.py
- Improved typehint support
- General readability improvements, made all string concatenations use f-strings
- Applied black formatting style to code
Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
