test of plotter helper modified
complex example implemented.
modified
created the spectra_average() method in the plotter_helper.py
Merge pull request #22 from lidiabressan/master

example implemented and test_plotter_helper modified
Merge branch 'master' of https://github.com/odarbelaeze/spectraplotpy
Merge pull request #23 from ariamania/master

created the spectra_average() method in the plotter_helper.py
Merge branch 'master' of https://github.com/odarbelaeze/spectraplotpy