Contribute optimizations to the python-mimeparse project

[kgriffs]

Optimizations may include:

• Cython support (simply compiling and/or *.pyx modules)
• Algorithms
• Micro-optimizations

Also consider simply implementing our own media type parsing and removing this dependency, or creating our own standalone project under falconry/*

[foresmac]

Doesn't look like this project has had any updates since 2016, and it's not a complicated library. But how often does one run into q values in an Accept header? Does falcon even really need what this ostensibly does? Couldn't we just pick the first match from Accept that falcon is configured to support? Honestly, I've only encountered a few APIs that support more than one serialization format.

[vytas7]

Now that python-mimeparse has been moved to Falconry, closing this issue in favour of falconry/python-mimeparse#45.