OpenGL Streamlining

Many changes made to the openGL rendering pipeline that increase speed and lower system impact. More improvements to come.

• Enabled multi threading for openGL
• Disabled unused states
• Removed unnecessary clears
• Reduced context switching
• Reduced state changes
• Reduced flushing
• Improved internal support for shaders
• General optimisations

New feature : 2 Channel Mixer

Added a new 2 channel mixer in processors, just blends between two inputs, with the option to set negative on either input.

Users a shader internally and much quicker than a QC mixer.

This new functionality changes the save file format, old files will open in the new version, but files created in the new version will not work with older versions.