Mcasm

- Added an Assembler property for allowing an implicit CFI procedure for the
text section

- Now building windows packages for Python 3.7, 3.8, 3.9, 3.10

- Fixed a performance regression added in 0.2.0 that caused creating Assembler
objects to be noticably slower

- Removed the C API
- Reworked the Python API to give even richer information by using a Python
extension to directly expose LLVM MC objects

- Added support for .align directives
- Fixed building on macOS

- Upgraded to LLVM 13.0
- Added Python type annotations
- Added additional information to sections