tinyrenderer: disable triangle backface culling (doesn't work well, cull triangles that should be visible)

GLInstancingRenderer: allow to set the light position

examples/TinyRenderer/TinyRenderer.cpp

@@ -426,14 +426,6 @@ static bool clipTriangleAgainstNearplane(const mat<4,3,float>& triangleIn, b3Ali
 {
 
 
-	float orientation = (triangleIn[0][1] - triangleIn[0][0]) * (triangleIn[1][2] - triangleIn[1][0]) 
-	- (triangleIn[1][1] - triangleIn[1][0]) * (triangleIn[0][2] - triangleIn[0][0]);
-	
-	if (orientation < 0.0) 
-	{
-		return true;
-	}
-
 	//discard triangle if all vertices are behind near-plane
 	if (triangleIn[3][0]<0 && triangleIn[3][1] <0 && triangleIn[3][2] <0)
 	{