BS Properties and BSVertexDesc changes

Use BSVertexDesc everywhere applicable.  Now passing in the entire compound as an ARG.  This means that a parser either has to treat BSVertexDesc as a uint64 and then shift to VF6-VF7, use & overloads for the class, or special case the class in some way.

Changed BS Properties fixed-size link array to two flat Refs as they are always a Shader Property and an Alpha Property and are dealt with flatly in-engine as well.