Cloth and spline geo in tyCache to inherit groups

[tyFlow]

The Material ID operator just assigns a single ID to each particle, which acts as a complete override on all matIDs of that particle's mesh. The material ID operator has no knowledge of what the particle mesh's mat IDs are. So you can have a shape mesh with 100 different IDs assigned to 100 different faces, and as soon as you apply a material ID operator, every face will get the single ID applied to that particle. In other words, the matID operator works on a particle level, not a mesh/face level.