- 1: Thin out GstGLDisplay for basis in a GstContext

- 2: test all the backends properly

- 3: finalize glmosaic element

- 4: write a GstGLFrameBuffer gobject. Would be usefull to factorize a lot of code in gstgldisplay.c

- 5: work out how a pipeline like this will work (currently only one sink displays a picture):
     videotestsrc ! glfilter ! tee name=t ! queue ! glimagesink  t. ! queue ! glimagesink

- 6: make a test to estimate how accurate colorspace conversion is. Compare an output frame
      to reference frame and estimate the differences. (usefull to compare several implementations)

- 7: test colorspace conversion with Apple YCbCr extension.

- 8: lift as much code as we can from eglglessink (shaders, VideoCropMeta's, VideoGLTextureUploadMeta, etc)

- 9: merge into gst-plugins-bad