put to_string() into StrHelper class. Reason: to simplify friend access
added prefix StrHelper to to_string()
converted to_string2() into template function
implemeted to_string() for SignalHandler, State, Fsm; implemented to_string2() for std::map
added friend class StrHelper
added friend class StrHelper
minor: added output of number of states in Fsm
added dumping of loaded Fsm
bugfix: keyword END was not handled properly
minor: refinement