Spafe

- improve code based on Joss reviewers recommendations.
- add type hinting.
- fix documentation typos.

- add spectrogram implementations.
- add predefined filter banks input to the spafe features functions for faster batch processing.
- add the Constant Q Cepstral Coefficients (CQCC) implementation.
- improve, restyle & add references and examples to the documentation.
- improve and simplify the code and the tests .
- inspect Cython and GPU accelerations to code (dropped).
- test support for different sampling rates (8kHz, 16kHz, 32kHz, 44100Hz, 48kHz).
- converters bug fixes.

- framing bug fix

- initial version