support for vraymultisubtexture

[Vance]

Multi-subs are supported, but you have to make sure your input geometry has proper material IDs assigned.

I'll try to put a sample together to show you the issue I'm having.   

My input geometry is 4 ty actors which have mat id ranges from 1 to 40. 

The id's are broken into four 10 id sections, one section for each character.  character 1  id's 1-10, character 2 id's 11-20...

The material applied to tyflow is a 40 id multisub.  

That all works fine but the issue is using the vray multisub texture to add random variation to one of the submaterial texture maps based on "random by particle ID"

Tyflow doesn't seem to read that value.

Thanks