GLMixer Code

First (sort of) working implementation of Undo Manager.

Fixed Preference and Settings issues (OSX)

Enable forced reload on web page stop.

Fixed update of Web Source.

Minor fix (compilation warnings, warning messages at runtime, etc).

Implementation of scaling and rotation of sources in Mixing view ready
for release. Added parameter for size of icons in mixing view and
improved icons for tools.

Updated readme

Finalized implementation of scaling and rotation of selection of sources
in Mixing View.

Catalog View does not use blending effects.