Reduced radius of self-referential edges by 15%.
Added an outline for edges.

Setting the stroke to a different value than the fill had weird effects
due to the way paths work. Used a filter instead. The problem is, the
filter does cause a bit of a performance hit. This is probably
something that should be turned into an optional feature toggled by a
button that is turned off by default.
Added highlight functionality.

Currently only highlights edges originating from the target node.
Bumped up the font size.
Added a semicolon.