Random permutation of FCMA

[yidawang]

1. add random voxel permutation to FCMA;
2. add more debugging and information logs;
3. minor tweak for docstring format, etc.

Thanks in advance for reviewing.

[xoltar]

Thanks, Yida! Looks pretty good, just a few small changes needed.

[xoltar]

_randomize_single_subject modifies data in place (and then returns the same array). _randomize_subject_list returns a new list, containing old arrays that have been modified in place, which is why these lines work even though you're ignoring the return value. I would say either write them both to work in-place, or write them both to return new values. Mixing the two makes for confusion. If you decide you want to have _randomize_single_subject return a new array instead of working in-place, consider numpy.random.permutation instead of shuffle.

[yidawang]

Thanks for the suggestion! Somehow I ignored the return value here although I should put it as activity_data1 = _randomize_subject_list(activity_data1, random). I would prefer working in-place, let me modify _randomize_subject_list accordingly.