Update Python bindings to support Python 3 (tested on Python 3.7)

[momonala]

First off, this is a great project! Thanks for making it open source.

I played around with it a bit, and I'd like to make a PR to update the python binding to support 3.X, as Python 2 is deprecated as of this year.

The main changes required were porting some C Python extensions over. Specifically, the Py_InitModule constructor has been replaced. Now I create a PyModuleDef structure and then pass a reference to it to PyModule_Create.

Additionally, I had to change the entry point of the compilation, by explicitly converting the application argument from char to wchar_t.

Other minor changes include:

• updating the .gitignore to ignore precompiled python files.
• updating the README and INSTALL markdown files.
• adding a requirements.txt file for pip.
• updating the example.py (scikits.audiolab.wavread is also deprecated).
• minor formatting, as per the PEP8 standard.

[sevagh]

Thanks, confirmed this is working for Python 3.8 as well.

Have you considered making it support both, by using ifdefs? E.g.

#if PY_MAJOR_VERSION >= 3

http://python3porting.com/cextensions.html