MRG: add infomax

cc @agramfort @fraimondo

still testing. works already fine but trying to understand some details with @jdammers.
yes!

> On Jun 19, 2014, at 9:14 AM, Alexandre Gramfort <notifications@github.com> wrote:
> 
> In mne/preprocessing/tests/test_ica.py:
> 
> > @@ -76,43 +76,46 @@ def test_ica_full_data_recovery():
> >      data = raw._data[:n_channels].copy()
> >      data_epochs = epochs.get_data()
> >      data_evoked = evoked.data
> how about a test_infomax.py file that can land in sklearn in a few months?
> 
> that way we can avoid testing all variants of ICA with both methods below.
> 
> I would copy as much test code from sklearn to test the infomax function
> 
> —
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