renamed nisl -> nilearn
BUGFIX: fit(...) method of MRIMotionCorrection class applied inverse of transformation instead of the transformation itself
REFACTOR: renamed nisl -> nilearn
BUGFIX: realignment was applying inverse of transformation instead of the transformation itself
ENH: loading vols only on demand. this was we avoid "too many open files" error thrown by nibabel (memmap)
ENH: added options interp_mode and interp_order in reslice_vols(...) API
fixed multiple tiny bugs