Java Backend Debugger (krun --debugger flag)

Contains changes to support the debugger option when KRun is run using the Java Backend. KRun can  be used with the --debugger flag.
Following features are currently working:
1) Step
2) Step All
3) Resume
4) Print State
5) Print Transition - shows rule, retrieved from the k file at the moment. Needed slight change to Java Rewrite Engine.
6) State Selection, viewing graph etc.

More features to be added. Maude debugger legacy code was not altered.