Port shadow shaders to singleton and remove non singleton.
Port stkbillboard to singleton shader
Fix ambient term.
clean up billboard text code
Enable ref + vertex color for unlit mat.
Text billboard uses unlit material.
Support vertex color for alpha ref material.
Fix shadows for unlit with alpha ref.
Use singletonshader template for colorize
Add a static assert.

Check if we pass correct count of uniforms name to AssignUniforms().
Better if we dont remove the real function call...
Forget the ...
Disable depth test in non dynamic light mode.

Just in case...
Merge remote-tracking branch 'upstream/master'