highlight active mode selection for graphs

- also replace buttons (with nested links) with
  links.
use utf-8 arrows instead of ascii-style arrows.
stub the links controller

In order to successfully resolve the graph
view, which contains hyperlinks to
links, we need the routes and a stubbed
controller.
fix linking to ontology content specifics

The URL that was used to link to
content specifics of a node (preds, sorts, sentences)
was wrong, since a new context was added to the handlebars
stack. Take care of this issue by traversing through
the stack by one level.