restructuring - moved sourceparcellate from hcp to ft, see #1775
enhancement - updated the documentation and added pre/postable, see #1775
enhancement - started with a test script
Merge branch 'master' into bug2085
enhancement - do not deal with backward compatible grad in ft_compute_leadfield, leave this to ft_prepare_vol_sens. Updated test script for #2085.
Merge branch 'master' into bug2085