Forces the user into topDown mode if the graph is selected in blockly

@BrettASwift @ajiraffe @kadst43 - Listing everyone but whoever is free first should be good.
The graph doesn't show up currently but can be added by entering the following into the javascript console.

vwf.callMethod( "index-vwf", "createGraph", [] )

Solves:
http://redmine.virtualworldframework.com/issues/3644