Add matchers support for transition Event types

[nsk90]

Now Event type argument of Transition is matched as "instance of". So there is no way to use Event hierarchy in transitions of same state.

[nsk90]

185e53bbc623fed1c41f576a777c428d516c96e2 adds matchers support, but there is no docs and tests, as I am not sure that current API is good enough.

• May be event matching is too complicated to use correctly
• May be it is better to allow user override State::findTransition() method?

[nsk90]

done in 11eeef4f