Add IMeshBuffer::getColor functions

Lazy access function - same as for all other members of S3DVertex (getPosition/getNormal/getTCoords).
Not sure why color was missing, maybe got added later?
Would probably be better to have a getS3DVertex function instead which would cover them all, but it's only some slow (but nice) helper function anyway.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@6415 dfc29bdd-3216-0410-991c-e03cc46cb475

include/CMeshBuffer.h

@@ -176,6 +176,17 @@ namespace scene
 			return Vertices[i].TCoords;
 		}
 
+		//! returns color of vertex i
+		virtual video::SColor& getColor(u32 i) IRR_OVERRIDE
+		{
+			return Vertices[i].Color;
+		}
+
+		//! returns color of vertex i
+		virtual const video::SColor& getColor(u32 i) const IRR_OVERRIDE
+		{
+			return Vertices[i].Color;
+		}
 
 		//! Append the vertices and indices to the current buffer
 		/** Only works for compatible types, i.e. either the same type