Fixed annoying bug whre if you dragged any part of the base image or other parts of the Drag and Drop problem, then the browser would start highlighting the elements.

Added mouse event handlers to container of draggable. Now it is easier to initiate a dragging operation.

Added correct handling of invalid (missing) base images. Now error is reported, and the damage is reduced to a minimum.

Fixed drag behavior. Now drag of icon itself rather than container element. This allows for finer selection (no overlap of transparent areas), and positioning of icon precisely onto a target. This breaks labels - TODO fix.