Docstring-to-markdown

Features:
- add bibliographic references parsing
- support numpy-style *args parameters: `arg1, arg2, ... : description`
- add mypy `py.typed` and fix mypy warnings

Bug fixes:
- inline-blocks of warnings and math are now correctly parsed

Features:
- signature detection (function/class signature in the first line of code)
- warning block detection
- kwargs and args in parameters detection

Bug fixes:
- lines after prompt (>>>)-specified code block are only interpreted as code output if there is no empty line in between