GLMixer Code

Display warning message when threads do not stop properly.

Added button in Log view to open the system folder with log files (to
help user find log files after a crash).

Fix names of FFGL plugins (too long for API).

Fixed bug of FreeFrameGL plugin source created from integrated glmixer
plugin.

Implementation of the Source Replacement functionnality (also copying
freeframe plugins)

Implementation of the Source Replacement functionnality (accessible from
the source Edit dialog) ; allows replacing the current source by a new
one.

Fixed issue with context menu in Geometry view (bug fix)

Fixed issue with context menu in Geometry view (right clic on selected
source was changing selection).

Cleanup & bugs fix.

Implementation of system logging (glmixer_log.txt file in temporary
system folder) and integration of more informative logging messages.
Cleanup and bugs fixed on the way.