GLMixer Code

Bug Fix: Looks like memory management is now fixed. Memory is freed from
libav internal structures and glmixer buffers (picture queue and packet
queue). Something still wrong with start/stop, which does not seem to
free memory immediately (but is freed when closing).

Bug Fix : cleanup memory in Video File

Trying to improve libav code

Bug Fix: cleanup of fill_first_frame to avoid blocking call of
avcodec_decode_video2

Bug fix freeze on error; Cathing decoding failure in VideoFile thread,
connected to the direct removal of the failing video source.

Bug Fix : freeze in reading first frame of video file (infinite loop)

Fix bug session manager (reload list after creation of a new session)

Code cleanup (deprecated Q_SIGNALS and Q_SLOTS)

Simplified opening of session (no busy indication, all events processed
before, etc.)