Work Progress - Jun 1 - Jun 7

Demo: "SB in beta" link above

Work done:
* Save the whole image instead of link of the image in the XML file. In other words, one is self-contained with a single XML file. This is an important step towards custom contents like custom audio.
* Allow change of background alpha, grid and grid number coloring as advanced properties of the background Engine.
* Provide a button in the toolbar for taking screenshot of the graphic window.