Merge pull request #65 from davidhesselbom/master

Merged.
Merge pull request #66 from davidhesselbom/master

Fixed a few leaks.
Added mipmap bool and now raising exception when trying to use unimplemented generateMipmap function.
Implemented generateMipmap for Yuv420Semiplanar.
Now sets mipmap to true when generating mipmap.
Fixed error in to3DTransformArray function, changed order of transforms and added function for converting to FloatTransform3D and returning array.
Fixed vertex shaders on Android.
Now disposes gpuimages that are mipmapped.
Merge pull request #67 from EmilWestergren/master

Fixed bug with mipmapped images, fixed error in FloatTransform2D