Added tentative icons for the new graph toolbar
Added new toolbar Ext class meant to replace the TXNGToolbar and PBCSToolbar classes we currently use
Rewrote LegendDef.js so that the implementation projects are responsible for assembling and defining their legend values in the implementation html.
Added "resizable: false" to the entity visualization tab definitions to prevent a non-functional click-and-drag handler from appearing around the border of each tab.