OPT: now possible to input mask in sct_register_multimodal (issue #181)
DOC: batch_processing now includes better registration for mt (issue #182)
OPT: now set default metric to MeanSquares (less errors when using mask)
OPT: sct_fmri_moco: set default group_size to 1
DOC: updated batch_processing
DOC: updated version