Update stats.py - Githubissues

I changed some comments here to correct language. A few questions/notes:

I changes "sensors" to "channels" throughout, except for the plotting. is that correct?
I added language clarifying that connectivity analysis takes an all-to-all approach in channel pairs
should we replace "electrodes" with "channels" throughout?
what does "a priori" refer to in the context of channel connectivity?

ppsp-team / HyPyP