gl: VideoShader class
Merge branch 'master' into gl
qml: sg node. not finished
color transformation supports in/out color space. add rgb

TODO:
other color spaces(XYZ, ...)
recompute matrix if ion/out color space changed
gl: always use qt's shader classes to avoid resolving gl symbols

glGetUniformLocation may be not declared in std gl headers
Merge branch 'master' into gl
gl: compute color matrix including yuv->rgb in cpu
gl: use planar shader. supports rgb
gl: VideoShader
add qt include and lib dir to config test
gl: more functions for OpenGLVideo
gl: less gl calls
gl: clearer rendering steps
gl: add VideoMaterial
gl: reduce matrix computation
gl: add ShaderManager to cache shaders & hi level api OpenGLVideo
gl: source files for VideoShader class
gl: avoid private class ColorTransform in public header
gl: helper functions for opengl to share with other sources