GLMixer Code

Creation of the Snapshot Manager.

BugFix in video file player on setting mark out (end).

Allow restoring settings of source creation dialogues (media and
shadertoy) and of restore of these settings when re-creating a source.

BugFix Source Edit replacement (recreate source option)

Implemented OSC properties for changing begin, end and timing of video.

OSC Broadcast of the information for connecting to GLMixer on start of
OSC server. Additional property for timing of a media file.

Added OSC properties to control playing of media source and videofile.

Updated the names of presets in MixingToolbox to avoid spaces so they
are compatible with OSC messages.

Added the OSC 'preset' attribute to sources : applies a preset from the
Mixing Toolbox from OSC.

Compilation fix for old G++ (before C++11).