Removed literallybackground() function to reduce plugin footprint
* adds backgroundImage option upon initialization
* adds new way of setting options after initialization without the need to reinitialize whole plugin
Allows to add custom buttons to bottom right toolbar
Allows simple colorpicker to add own colors upon initialization (including transparent!)
Remake of Rectangle Tool & Widget
* now supports transparent (with variable strokewidth) or opaque rectangles
Removes redundant open as image button on demopage