Option for getting dipole time series (w/o collapsing orientations)

[matsvanes]

We typically work in parcel space, but we already have a function to get the "voxel" time series of beamformed data (i.e., amplitude, so after collapsing the orientation information). It could be useful to have a function that returns the dipole time course in each direction, for example when you expect crucial information to be represented in the orientation of the dipole.