GLMixer Code

New icons for new Layout actions

Added aspect ratio transformations to Layout Toolbox (and also reset of rotation and of flip).

BugFix: fixed reordering of sources when changing depth in Layers View.

Compilation improvements for FreeFrame under Windows.

BugFix: no support for JavaScript in QWebKit under Windows.

BugFix: important fix in the changing of depth of sources (mostly occuring in Layers View).

Fix Windows 10 compilation

Oooops.. Restore signals & slots of MixingToolbox (broken previous commits...).

Fixed and improved Video file dialogs.

Updated default GLMixer toolbox and window layout to match new widgets.