ENH: Start using joblibs
ENH: add n_jobs for MRI
ENH: Use np.array_split to make jobs CPU bound, not IO bound
ENH: Create VALID_EXTENSION global variable
FIX: Cleaner flattening + unique value finding
DOC: Add comments to private functions.
FIX: Whitespace issue
Merge pull request #1440 from mainakjas/mne-report-n_jobs

ENH: Add n_jobs to report