Bug fix #1988, ray-transparency render.

Five fixes in this commit...

- the normals for nurbs surfaces still were calculated pointing wrong in some occasions
- recoded ray-transp rendering to accept normals pointing any direction; it just counts how many times it passes a "glass" layer, and flips normals appropriate then. This means rendering will go fine on models without manually setting the normals. You can also move a camera inside a 'glass' object.
- rendering of the inside part of glass now uses correct normal too... specularity happen on a solid glass inside now.
- And an inside reflected mirror ray will keep bouncing inside glass

Related to rendering localview: old convention to render localview, but with the lamps in the normal layers, has been restored.
Please note; render happens based on active window. You *only* get a localview or 'unlocked layer' render when that 3d window is active = mouse in window.

source/blender/src/renderwin.c

@@ -967,8 +967,12 @@ void BIF_do_render(int anim)
 	/* if start render in 3d win, use layer from window (e.g also local view) */
 	if(curarea && curarea->spacetype==SPACE_VIEW3D) {
 		int lay= G.scene->lay;
-		G.scene->lay= G.vd->lay;
+		if(G.vd->lay & 0xFF000000)	// localview
+			G.scene->lay |= G.vd->lay;
+		else G.scene->lay= G.vd->lay;
+		
 		do_render(NULL, anim, 0);
+		
 		G.scene->lay= lay;
 	}
 	else do_render(NULL, anim, 0);