Fix crash when replacing shader with unshadowed or non-specular variation, and geometry type is something else than static.
Add billboard variation to Vegatation shader. The effect is not very good though, as the billboard vertices do not move individually.


git-svn-id: http://urho3d.googlecode.com/svn/trunk@2629 3bd170d8-ddcf-f82c-f583-7a401ccf5608