Add python interface

[lucastheis]

Hi @kazuho, I've implemented a Python interface and some unit tests for your range coder. I've tested it with Python 2.7, 3.4, and on Linux and Mac. Let me know what you think.

[jsiloto]

@lucastheis I can't use this lib. Could you help me?

$ pip install -e rangecoder
Obtaining file:///tf/rangecoder
Installing collected packages: range-coder
  Found existing installation: range-coder 1.0
    Can't uninstall 'range-coder'. No files were found to uninstall.
  Running setup.py develop for range-coder
Successfully installed range-coder
WARNING: You are using pip version 19.1.1, however version 19.2.2 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

from range_coder import RangeEncoder, RangeDecoder
from range_coder import prob_to_cum_freq, cum_freq_to_prob

ModuleNotFoundError                       Traceback (most recent call last)
<ipython-input-17-3f5fb52f5f83> in <module>
----> 1 from range_coder import RangeEncoder, RangeDecoder
      2 from range_coder import prob_to_cum_freq, cum_freq_to_prob

ModuleNotFoundError: No module named 'range_coder'

[lucastheis]

Sorry, I do not know why your Python cannot find the range coder. Maybe you have multiple versions of Python installed and added the range coder to the wrong one?