add basic debug drawing interface for btMultiBodyPoint2Point constraint

add basic debug drawing drawText3D in SimpleOpenGL3App
remove a few warnings
add drawTexturedRect3D to GLPrimitiveRenderer to support debug drawing

Demos3/bullet2/CoordinateFrameDemo/CoordinateFrameDemoPhysicsSetup.cpp

@@ -21,6 +21,7 @@ void    CoordinateFrameDemoPhysicsSetup::debugDraw()
 		}
 	}
 	*/
+
 	m_dynamicsWorld->debugDrawWorld();
 }