Cleanup: Renamed compositor executePixel functions and their 'read' wrappers in SocketReader.

Distinguish the 3 different methods for acquiring pixel color values (executePixel, executePixelSampled, executePixelFiltered).
This makes it easier to keep track of the different sampling methods (and works nicer with IDEs that do code parsing).

Differential Revision: http://developer.blender.org/D7

source/blender/compositor/operations/COM_MapUVOperation.h

@@ -45,7 +45,7 @@ public:
 	/**
 	 * the inner loop of this program
 	 */
-	void executePixel(float output[4], float x, float y, PixelSampler sampler);
+	void executePixelSampled(float output[4], float x, float y, PixelSampler sampler);
 	
 	/**
 	 * Initialize the execution