Unfortunatly, porting GraphViz to Java of requires a lot of time, so this has been postponed.
We are aware that depending of GraphViz is a issue for some users, but the only workaround you may try, is to
use some portable version of GraphViz:
https://github.com/mlf176f2/GraphVizPortable
http://gc.codehum.com/p/graph-viz-portable/downloads/list
We did not test them.
If JDot comes back, we will put some news, but do not expect anything this year.
Regards,