Merging from pull.
general plotting spectra tool.
Added functionality to plot multiple spectra.
Added comments to plot_spectra.
Importer corrected and test_importer improved.
Corrected a bug.
add corrupted file for check.
Completed test
Merge branch 'master' of https://github.com/odarbelaeze/spectraplotpy

Conflicts:
	spectraplotpy/importer.py
	test/test_importer.py
Merge branch 'master' of https://github.com/odarbelaeze/spectraplotpy
Just an update