Added refinement and masks for Loop subdivision:
    - added flag to Sdc MASK interface to interpret "face weights"
    - updated Catmark and Bilinear schemes to be aware of new MASK flag
    - added subdivision and limit masks for the Loop scheme
    - subclassed Vtr::Refinement into QuadRefinement and TriRefinement
    - updated tagging of components to be sensitive to applied scheme
    - fixed some quad assumptions in FVar refinement to support N-sided
    - internally generalized ::TopologyRefiner Interpolate() for <SCHEME>