GLMixer Code

Implemented generic source play method for playing the plugins of that
source.

Bugs fix Win32 implementation of Shadertoy plugins

ShaderToy plugin for Win32

Added win32 qrc.in

Working implementation of Shadertoy plugin with GUI
+ bug fix texture wrap in FFGL plugin
+ deactivation of context menu 'defaultValue' because it is not
implemented

Bugs fix for GLSL Shadertoy editor
- edit option context-reactive in context menu
- unlink editor when plugin changed (could be improved)

Shadertoy Plugin implementation : saving and loading in XML glm file,
options and help in GUI,

Implement reset of Shadertoy code + bugfix.

Implementation of ShaderToy GUI (Code editor with lineCount, actions of
buttons)

Continuing the implementation of ShaderToy FreeFrame plugin:
- changed functions for adding a new FFGL plugin to return pointer to
FFGLPluginSource
- Fixed mechanisms for initialization of FFGLPlugin
- fixed GUI for GLSL code editor