EventDispatcher upgraded for threadsafe usage #74

[XIII-th]

This commit fix #74 issue

[czyzby]

Removal from array lists is noticeably slower than from sets/linked lists (during iteration). This is likely to be a premature optimization and won't be an issue unless someone builds the whole app around Autumn events, but I feel the SnapshotArray is not the right collection to solve this. I'll look into your pull request more thoroughly before the next release though.

[XIII-th]

@czyzby right. Removal via iterations it't bottleneck of this solution, but I'm using Autumn more than four months in my game and I don't found at least one case for automatically event/message listener removing. Event/message listeners is used for user interactions, networking, and even for realtime game rules checks.

I realy think, automatical removing of events/message listeners - it's something really specific. Developer can manually do this via removeListener() if need it.