Patch for bug #895106

[Frank C <li...@si...>]

Here's a few modified files:  
<http://webhome.idirect.com/~frankco/895106patch.zip> that fix bug  
#895106 "Colours have no effect on textured geometry"  
<http://sourceforge.net/tracker/index.php? 
func=detail&aid=895106&group_id=45158&atid=442052>.

This patch mimics QD3D 1.6's behaviour, modulating vertex colours with  
textures for null shaded geometry, as described here:  
<http://developer.apple.com/documentation/QuickTime/QD3D/ 
QD3DDelta.htm#_Toc438524142>. It also unifies a temp fix from the  
trimesh renderer that prevents lit textured geometry from modulating  
vertex colours when going through the tribuffer path.

This patch appears to work in all my test cases, but I'd appreciate any  
criticisms or improvements!

Thanks,
Frank.