GLMixer Code

Fixed compilation for USE_OPENCV cmake flag.

Fixed (last?) bugs of shared memory source (stop the source in case of shared memory problem).
+ added GNU copyright for files which didn't have it.

Fixed mechanism of creation and start & stop of shared memory source (to rescale texture when re-attaching).
Simplified the glmixer event for action 'start' button (with a startCurrentSource method in manager).
Cleared setCurrent mechanism in rendering manager

Set shared memory sources to PLAYABLE (i.e. implemented play on/off mechanism).

Changed saving of shared memory sources.

Fixed shared memory management of color depth (16, 24 & 32 bits) and auto detection of changes in shared buffer (size).
Changed frame buffer alpha to 0 (to enable transparency).
Added preference for shared memory color depth.
Added support for vertical flip of source with a flag (to support inverted images from shared memory).

Implementation of fullscreen mode.

Fix compilation with different cmake build directory.

Implementation of signal mechanism to detect changes in the source properties.
Using this to propose to save a session when closing if it has changed.

Avoid copy (rename) of the temporary recorded file when saving in automatic saving to folder mode.
+ remove property "attached" for shared memory source.