Calculate and save projections onto cluster means

[lshaheen]

Hi,

Would it be easy for Kilosort to calculate and save the projections of each spike onto the cluster mean waveforms? Like the template projections, it could somehow only be for nearby clusters. In cases where Kilosort does splitting and merging after the main algorithm this would be especially helpful, because right now you're not able to visualize the projection KiloSort used in splitting.

This might also resolve https://github.com/MouseLand/Kilosort/issues/317