Add basic comparision plots function.

[BHbean]

Implement basic comparision plots function.

• Encapsulate python scripts into an executable audio-plot. The possible arguments are as followed:

  
  usage: plot.py [-h] [-b {head,body,tail,all}] [-p PORTION] [-n POINTS]
             [--nosave]
             file1 file2

This module is designed for figure plotting.

positional arguments: file1 The path of the .wav file before process. file2 The path of the .wav file after process.

optional arguments: -h, --help show this help message and exit -b {head,body,tail,all}, --part {head,body,tail,all} Choose a part of the time-domain figure to show. Possible values are "head", "body", "tail" and "all". -p PORTION, --portion PORTION Decide the portion(between 0 and 1) of the wave to be shown. Note once this argument was specified, the "-- points" argument would be invalid. -n POINTS, --points POINTS Decide the number of points of the wave to be shown. --nosave Decide whether or not to save the figure.

- Users can specify `python3` command used by adding the option `-DPYTHON_BINARY_DIR=/PATH/TO/PYTHON/BIN`, and should make sure that `numpy`, `matplotlib` and `scipy` packages are installed previously.