Add epoxy: A library for handling OpenGL function pointer management
Add movit: High-performance, high-quality video filters for the GPU

NOTE: movit expected to be able to read source files from gtest, so I
also made them available.

squash
Add frei0r: Minimalist, cross-platform, shared video plugins
Kdenlive: 0.9.6 -> 0.9.8, add frei0r plugins, add myself to the maintainers
MLT: 0.9.0 -> 0.9.2, add movit and frei0r plugins, add qt4 and qt5 variants

Shotcut segfaults on startup when compiled against an MLT which was
built with qt4. Kdenlive seqfaults when compiled against an MLT which
was built with qt5. Hence the need for the two variants.

Also, I'm adopting MLT as a maintainer.
Add Shotcut: A free, open source, cross-platform video editor

Includes a patch which has already been applied upstream:
mltframework/shotcut#31
frei0r: fix typo
Merge branch 'shotcut'

Add Shotcut (video editor), update Kdenlive and MLT, add frei0r and movit plugins