Enabling Xcode style warnings in appledoc.

This will generate tons of warnings in Xcode for undocumented stuff, but only in the Documentation target.
Added a ton of appledoc comments
Merge branch 'master' of https://github.com/BradLarson/GPUImage

Conflicts:
	framework/Source/GPUImageHarrisCornerDetectionFilter.h
	framework/Source/GPUImageVignetteFilter.h
Added a tone curve filter, submitted by Marcelo Barbudas.
Merge pull request #129 from wjlafrance/master

More docs!
Fixed issues with the crop filter not properly recreating FBO sizes after filter removal and replacement.
Added a new raw data input class. Fixed download issues with the raw data output. Fixed the ColorObjectTracking example.
Trying again to commit raw data fixes.
Added a blur size property to the box blur, and modified the adaptive threshold to use it.
Added ability to control whether raw bytes are read out as BGRA or RGBA, made that consistent across iOS versions.
Added a test application for feature extraction operations. Improved the sensitivity of the Harris corner detector.
Split out the Noble variant of the Harris corner detector and added the Shi-Tomasi feature detector.
Added timestamps for feature detection.
Integrating Marcelo Barbudas' alpha channel fixes for the color dodge, exclusion, hard light, soft light, multiply, and overlay blends. Tried to vectorize the color dodge blend.
Fixed a precision issue and some divide-by-zero problems with the color dodge blend.
The Canny edge detection now actually follows the specification, so it finally works right. Fixed a double-free error with shader programs.
Updated some documentation around the new Canny filter.
Added a fix for a compilation error and a quick check to reduce redundant context setting calls.
Tried to fix a calculation issue with the tone curve filter. Tried to fix a problem with the second texture on blend filters.
Added a check to remove the one analyzer warning.