Adjusted the bounds and the layout, fixes #22.
Cleaned up the code for creating icons.
Consolidated code for adding removal listeners.
Cleaned up some workarounds for the bucket positioning that were done because the buckets don't support inverted Y positioning.  This impacted common code.
Cleaned up a TODO comment.
Code cleanup - various TODOs and such.
Removed the RectangleCreators from the exploration model and made it such that the creator nodes are only in the view with no corresponding model element.  This is simpler and more consistent with how things are done in the game screen.