Introduced new Cytoscape wrapper class.  Changed constructor to reflect this in Transaction and Entity graphs
Minor fixes to prevent or modify default behavior of GUI elements
Added a "Snap To" button to the graph toolbar.  If you pan or zoom too far out to find your graph, click this and get it back.  The previous layout is preserved.
Fixed a scoping issue in the radial context menu
Added stubs for node hover popup and the ability to get a formatted set of the currently registered layouts at Eli's request
Added Dijkstra algorithm (i.e. shortest path between two nodes) capability, tied to right- and left-click user actions.

Note: by adding this capability, I uncovered a glaring issue with maintaining scope in the RadialContextMenu.  Until it has been addressed, each CytoGraphVis will instead create its own cytoscape.cxtmenu instead of using the RadialContextMenu singleton.