GLMixer Code

BugFix: correct implementation of source crop (computation of texture
coordinates was wrong) and of minimal source scaling with clampScale().

BuxFix: correct implementation of context menu in property browsers
(source properties and freeframe plugins).

Don't forget to install freeframe shake plugin.

Split code of Clone source in .h and .cpp

Fixed management of clone source (bad copy of properties, correct copy
of plugins, etc.).

Bug Fix: do not use static variables in Freeframe plugins (cannot manage
instance creation, causing problems with multiple use of a plugin).

Fixbug : saving recording after selection of filename.

Bugfix: unload freeframe plugin when done testing in effect selection
dialog.

Fixed synchronization of PTS in video file.

Removed the software filter of libav in video file (archaic and useless).