v1.9.15

-- Added hmrR_DeconvHRF_DriftSS.m to list of user functions. Tested against Homer2 output for 2 data sets.
-- Fixed long-standing and nagging problem in group and subject block average functions hmrG_BlockAvg and hmrS_BlockAvg where calculating grp1 averages generates matlab error because of dimensions mismatches when adding vectors  (row vector vs column vector). Fix was to makes sure to add 2 column vectors.
-- Fixed a few other small bugs in user functions prune channel and motion artifact.