ClassifyPoints and point_class should be removed from Carpet since right now they always set the class to 1.
There is interest in having the functionality that the routine and grid function provide, namely to know at which MoL substep we need to have valid data at a given point (eg. for con2prim and con2prim failures as well as possibly skipping computations in buffer regions that are no longer valid). This could be added to CarpetEvolutionMask quite straightforwardly, but might require some redefinition of the mask values, eg. 0 for valid in all MoL substeps, 1 valid until and incl substep 1, ..., MoL_Num_Intermediate_Steps-1 valid only during the first substep, MoL_Num_Intermediate_Steps for restricted points. This would mean eg an analysis routine can ignore anything >0 while an evolution routine would have to check with MoL.