ica.get_sources has strange ch_names and ch_type

After calling ica.get_source() with a Raw object I noticed that

• the ch_names “ICA 001” start by 1 instead of 0 (which is not consistent)
• I couldn’t plot it right, as the ch_type for scaling is not clear (it seems to be misc, but I couldn’t find any documentation about it)

I would suggest to let the ICAs start by 0 everywhere. Remove the +1 here: https://github.com/mne-tools/mne-python/blob/master/mne/preprocessing/ica.py#L798

[larsoner]

So over in #4320 the crushing weight of a half dozen (or more) opened issues/PRs about this issue has caused @agramfort to have a change of heart to accept the possibility of naming channels as ICA 000+. It creates inconsistency with other channel names, but IMO (and maybe @agramfort has come around to it, now, too) this is less bad / create fewer problems than our current solution, where most users are confused by our ICA interface.

@dengemann @jona-sassenhagen @jasmainak @mmagnuski are you okay with this change?

@mmagnuski would you perhaps be up for making a PR?

[mmagnuski]

I also think that ic numbering inconsistency is counterintuitive (and changing the docs won’t change the intuitions 😉 ). ica.plot_sources plots sources with names in IC #000 convention - which is good as it makes comparisons between plot_components and plot_sources easier, but further increases surprise when ica.get_sources().plot() gives other labels (ICA 001). If channel labels must of form ICA 001 - then maybe ICA plotting functions should print ICA 001 instead of the index? Or maybe both should change to IC 001? 😈