MRG: revamp ICA

New API for ICA, shorter examples, new diagnostic plots, utils for generating epochs on artifact events, outlier detection ....
I know it's gonna  be difficult to review but from time to time PRS like this one are necessary.
Please don't review. I'm in the middle of debugging.

cc @jdsitt @fraimondo @agramfort  
> 0/ score returns a log lik so it's always negative unless this is a normalization bug
@agramfort it's not look up the code in mixture ... it's a difference score

> 1/ you cannot guarantee the order of the components.

mhm ... needs closer inspection

> 2/ you could use score_samples to know if which gaussian a mixture belongs

indeed. the bad one should have less summed responsibility

> I feel you're addressing a not so easy problem which is a pain and prevents
merging for the great new API

we can use the old z-score here. and keep it for later