Added plotter write to directory ability (heatmap)
Fixes to plotter:

  Fix graph labels
  Fix aspect ratio
Added write and no-view options
Add file plotting capabilities:

  Can parse explicit file name argument
  Accepts files to write
Use vstack instead of generating large array
Cleaning up tests

  Use np.testing rather than assertTrue
  Add descriptions to plotting tests
  Add descriptions to frame_parser tests
  Improve documentation
Add outlier specification option