Point Labels

[joshheinrichs]

It'd be nice to add point labels, but I need to be careful about redrawing text, since it's very slow. Edge labels would be nice too, but are less important. These should be togglable.

[joshheinrichs]

The performance problems associated with redrawing text were solved following this: http://stackoverflow.com/questions/26536841/javafx-animation-poor-performance-consumes-all-my-cpu

This might be useful for vertexes as well, but since they aren't causing performance issues, I'll leave this optimization until later.