try reusing the same center node to see if it fixes color matching issue (it doesn't)
delete dead code
3/19/13 add bootstrap controls for switching between shaker and dropper (not wired up, not correct look)
3/19/13 add DOM controls to scenegraph last, so that they are not obscured by canvas-based nodes and receive DOM event
3/19/13 add debug output for setVisible problem in ShakerNode and DropperNode
3/19/13 wire up Solid and Solution buttons