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
this node allows for more control for normalization of the mapped input range.
Made during BlenderPRO 2012 - Brasilia, Brazil :)
Idea and testing: Daniel Salazar
Implementation: yours truly
Reviewed by Lukas Toenne and Sergey Sharybin