Added class 'Curve' to namespace; modified class 'Polygon' to be based on curves rather than vertices alone.
Class 'Polygon' features function to interpolate the bezier-curve formed by it's vertices.
Added support for left, middle and right mouse button. Disabled contextual menu for the canvas element.
Widget instance tool objects dynamically by their name. Simplified toolbar-button creation.
Added comments. Cleaned some nasty indentions.