Adding some other files to the documentation.
Merge branch 'master' of https://github.com/odarbelaeze/spectraplotpy
Plot functions added with full capability.
plotter helper implemented consistently with the plot functions.
Merge branch 'master' of https://github.com/odarbelaeze/spectraplotpy
Merge branch 'master' of https://github.com/odarbelaeze/spectraplotpy
finalized the mock test for plot() and errordata() in test_spectrum.py