Grass Enable GPU instancing

yeah, you select texture only when selected "Grass" or "Billboard", otherwise you select prefab and prefab have material with custom grass shader with wind etc... and its start to work with flag "Use GPU instancing" that make "render mode vertex lit" parameter grey (disabled and ignored as i understand)... so i just need to make that "Use GPU instancing" set true automatically otherwise I must set this flag 16 times on every grass part manually after any node change.

#1792