adding color monochrome
Change SimpleVideoFilter Demo to allow all orientations.
Fix PortraitUpsideDown rotation on the back camera.

The back camera is natively landscape left, therefore upside down is a left rotation.
Added kGPUImageRotate180.

This is needed for the back facing camera on landscape right, since the back camera is left facing landscape.

NOTE: Since a 180 rotation is a flip vert and a flip horz, and both of those are marked as broken in GPUImageCropFilter's -calculateCropTextureCoordinates, so is the additional block to handle rotate180.
Fix front facing camera.
Fixed some compilation errors with the latest Xcode. Started experimenting with a sphere refraction shader, which is currently broken.
Fixed the histogram filter in the FilterShowcase, after I broke it with one of the last few commits.
Merge branch 'master' of https://github.com/alariccole/GPUImage

Conflicts:
	framework/GPUImage.xcodeproj/project.pbxproj
Added the monochrome filter to the showcase.
Added method to get the targets from a GPUImageOutput
Added an image buffet filter that delays frames, allowing for comparative processing of sequential frames. There are some slight issues with timing on the blends that I still need to fix.
Merge pull request #226 from acoomans/master

Added method to get the targets from a GPUImageOutput
Texel distances should be set properly for rotated images in a couple of filters now.
Fixed the GPUImageMaskFilter.
Added ability to enable/disabled GPUImageOutputs - fast way to turn them on or off. Replaced all references to self in blocks with __unsafe_unretained __typeof__(self) weakSelf = self; Added method to GPUImageStillCamera to take a photo and retrieve the CMSampleBufferRef directly. However, I left this method commented out, as to use it you have to have the camera pixel format in its native setting, which is incompatible with GPUImage.
Merge pull request #238 from iSkythe/master

Ability to enable/disable GPUImageOutputs. Replaced all references to self in blocks with __unsafe_unretained self. Added method to retrieve the CMSampleBufferRef directly from GPUImageStillCamera
Tweaked some of the weak self references to avoid compiler errors.
Added a filter to adjust the incoming opacity of images.
Merge pull request #201 from Philippe23/video-orientation

Fixes for video orientations & mirroring.
Added a compiler define to check whether this is on the Simulator, disable the texture caches if so. This should enable limited use with the Simulator.