Corrected a failed refactor - return StateBuilder not base

When enhancing the StateBuilder interface with conditional transitions
the methods were pulled up from the base class.  This set the return
value of the methods as the base class.  This is definitely not a good
design practice; returning the implementation from the interface can
have very bad side effects.
Merge branch 'master' into context

Conflicts:
	src/main/java/com/bnorm/fsm4j/StateBuilder.java