Tone curve filter: bug fix, always add the last point as it is never added.

Previously the last point would not be added correctly if the last point's x < 1.0 as there would be fewer than 255 entries in the output array. So the output points would approach but not actually get to that final point.

If the final point was y=1.0 it wouldn't matter as we go on to extend the returned array out to x = 255 with y = 1.0s. But if it wasn't then we'd miss that last value.

Also clarified the question in comments about whether the length of the points array is equal to the length of the second derivative. It is. Also made the n variable a constant in the second derivative method to ensure it.
Tone curve filter: correct application of RGB in conjunction with R, G, B channels.

The RGB adjustment must be made after the R, G and B adjustments.
Also build GPUImage as static framework in build.sh
GPUImageTwoInputFilter newFrameReadyAtTime can't always pass on frame time from the first input

Sometimes the first input will be a GPUImagePicture with a frameTime of CMTimeIndefinite. I have added a check to see whether the firstFrameTime is indefinite, in which case the secondFrameTime is used.

The behaviour will be the same as before, unless the first input is a GPUImagePicture then the time will be used from the second input. Because the frameTime will always be indefinite it will always use the second frame time and therefore will be stable.
fix a couple of memory leaks
Merge pull request #1098 from erysaj/fix-memory-leak

fix a couple of memory leaks
Merge pull request #1071 from karlvr/tonecurvefixes

Tone curve filter: fixes missing last point and incorrect application of RGB curve in conduction with individual channels
Merge pull request #1094 from karlvr/two-input-frame-time

GPUImageTwoInputFilter newFrameReadyAtTime can't always pass on frame time from the first input
Merge pull request #1077 from howanghk/build-static-framework

Also build GPUImage as static framework in build.sh