Added logging on fire() and toString for triggers with params

Thanks for changing to slf4j!
I've added a line of logging to the fire method that logs the complete state change with source/destination state, trigger with parameters.
Introduced in J1.5, the annotation is not required but indicates to the compiler (and other/later developers) that this method should override another.
Imagine having a typo in the method name and wondering why only the code in the super class gets executed insted of the overloaded one (been there, done that :-).
My eclipse adds them automatically, I fear. Perhaps I'd better switch that off for this project? There is also some 'remove trailing spaces' and 'organize imports'...