HDR and Tone mapping

[AlexMarinescu]

Implement an HDR rendering pipeline by adding support to load HDR textures, render bloom/gaussian blur and a few tone mapping shaders. Tone mapping will be similar to Uncharted 2 and some very generic ones.

[AlexMarinescu]

Currently working on support .HDR and .PIC format, I will add the ability to create those types of files as well. I will eventually look into maybe supporting .float file types although there is no benefit over .hdr/.pic.