[Post-processing] logic rework, cleaning, & added cel shading.

Just tidied up the code, reworked some logic for the tone mapping, sharpening, and scaling. Also adding the preliminary shader code for palette textures. I still have to do the code for the annotations yet though. 

Example screenshot of the tone mapping & bloom with demo(exaggerated) shader settings in Divinity: OS here: https://flic.kr/p/pNgf8e

I need to upgrade from VS2013 Express, as it has no ATL support >.> So, I've only been able to do some work on the external stuff so far.

-------
ps: I messed up a previous fork sync, so I closed the last pull request, and just opened a fresh one.