Add radius and center to GPUImageGaussianBlurFilter

No performance impact on iphone or ipad noticed
GPUImageToneCurveFilter # initWithACVData added
Fixed framework under iOS 4.x. Fixed the bulge distortion filter, which was triggering crashes on certain devices.
Add GPUGaussianBlurPositionFilter and restore the original code for GPUGaussianBlurFilter
Fix compile errors for new blur filter
Added cancelRecording method to movieWriter

Added simple wrapper for AVAssetWriter cancelWriting based on
movieWriter finishWriting in order to cancel a recording and avoid
flushing the file to disk
Merge pull request #700 from jjxtra/master

New GPUImageGaussianBlurPositionFilter
Merge pull request #731 from chrisben/master

Added cancelWriting method to MovieWriter
Fixed issues with uniforms not updating on multiple instances of the same filter, while still maintaining shader program caching.
A5 devices now take in camera data as YUV, speeding frame processing from 2.2 ms to 1.5 ms on 4S. No impact on memory usage, surprisingly.
ARC forbids explicit message send of 'release'; since iOS 6 even for dispatch_release() calls: stripping it out in those cases is required. Use iOS 6 version value instead of macro for comparisons because we might get compiled on an old OS that does not define a later.
AVAssetWriter –finishWriting is deprecated in iOS 6.0; switch over to the new -finishWritingWithCompletionHandler: for that version and up.
Added YUV camera support to non-A5 GPUs. Added full-range YUV for better color reproduction. Fixed a crashing issue with YUV code on the iPhone 4.
Merge pull request #758 from raphaelschaad/master

iOS 6.0 Compatibility
Fixed compiler macros for targeting iOS 6.0.
Add color, hue, saturation and luminosity blend modes.

With formulas based upon the PDF specification which matches Photoshop behaviour.
Linear burn blend filter
Merge pull request #762 from karlvr/colorblends

Add color, hue, saturation and luminosity blend modes.
Fix defects as described in issue #654 - filters using a lookup filter would not update with new input.
Now passes luminance plane directly into filters that need grayscale, significantly improving performance for edge detection and related filters. Fixed a bug with the iOS 6.0 feature detection macro.