Fix issue 1580
Merge pull request #1716 from zmzhuai/master

Fix issue 1580
Added an example of how to use Swift playgrounds with GPUImage.
Incorporating the crashing fix by robmaceachern from here: https://github.com/robmaceachern/GPUImage/commit/fd4e39b2079057064f9549a7911ad7ea31e0ad62#diff-d41d8cd98f00b204e9800998ecf8427e
Update GPUImageHistogramFilter.h
Added support for fast texture upload
Added new histogram equalization filter
Added new histogram equalization filter
Added new histogram equalization filter
Added example of new histogram equalization filter
Added example of new histogram equalization filter
Added example of new histogram equalization filter
Update GPUImageHistogramEqualizationFilter.m
Update project.pbxproj
Update project.pbxproj
Merge pull request #1736 from amarcu5/master

New histogram equalization filter
Merge branch 'upstream'