Move big chunky pixel colors to separate function

Again, to make sure colors don't update more than 1000/34 frames a
second, we'll need to separate this color calculation from rendeirng
functions.

desktop_version/src/Graphics.h

@@ -34,6 +34,7 @@ public:
 
 	void drawhuetile(int x, int y, int t);
 	void huetilesetcol(int t);
+	Uint32 bigchunkygetcol(int t);
 
 	void drawgravityline(int t);