CSQC polygonbegin functionality now uses the CL_MeshEntities system, this finally...

CSQC polygonbegin functionality now uses the CL_MeshEntities system, this finally makes it possible to use shaders on those polygons.

UI elements (DrawQ_ system) now use the CL_MeshEntities system, but still renders the mesh the old way, shader support is planned.

DrawQ_Line no longer uses GL_LINES, it now produces a polygon in the CL_MeshEntities system, so shownetgraph and r_speeds_graph features now work on D3D9/DPSOFTRAST/GLES2 render paths.

Added MATERIALFLAG_VERTEXCOLOR as a special case for rgbgen vertex shaders that are being used by CL_MeshEntities meshes, currently this is an unlit type of material but lighting support for it is planned.

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@12388 d7cf8633-e32d-0410-b094-e92efae38249