Remove Eigen3 and Movit third party source.
Adapt opengl module to movit as external lib.
Change GL_TEXTURE_RECTANGLE_ARB to GL_TEXTURE_2D.
Factor out VerticalFlip Effect.
Make GlslManager EffectChain methods more generic.
Add a Movit FBOInput to feed a chain from rendered FBO.
Add movit.mix transition.
Fix crash in movit filters on blank frames.
Add movit.overlay transition.