ENH/FIX: improve logcosh function + tests
FIX/ENH: revert changes, improve doc
FIX: 80 characters
COSMITS
COSMITS
COSMITS
ENH: address discussion
ENH: use empty, not zeros
COSMITS
Merge pull request #2290 from dengemann/more_ica_improvements

[MRG]: improve logcosh function + tests