WIP: Introduces PointToCellMap

This is from earlier work and never completed but pinning it here in case someone finds it useful later. I may pick it up later too.

This effectively introduces automatic computation of linear blend skinning weights. We have an animation branch that can apply linear blend skinning to bones only. It does not do the weight computation though. Similarly we have PointToTetMap which uses and applies vertex weights sums, but it fails to deal with the edge/joint cases to linear blend. This MR was a first attempt at implementing weight computation for a PointTo any cell map. For instance, PointToLineMap (for thick and geometrically interesting threads) or PointToSurfaceMeshMap (for thick cloths from thin simulated tissue).

Note: This also stems off another required branch resulting in an extra commit that shouldn't be here.