We have a new multi-band processing scheme for coadds on the HSC side, encompassing changes in afw, meas_deblender, and pipe_tasks. These should be transferred to the LSST side, with RFCs for any backwards incompatible changes.

Changes to the Footprint classes may only be temporary, as we plan to refactor those classes soon anyway, but they're still worth doing now to support the higher-level changes.