removed superfluous deregistration of local hander of local event. After the finalizer is executed neither will the event occur ever again nor can the handler hinder garbage collection.
Furthermore the usage of the Dispatcher can proof dangerous if used when doing AppDomain.Unload (possible deadlock?!)
removed superfluous "emptyDelegate" definition.
Merge pull request #1584 from BrunoJuchli/master

Preventing deadlock on AppDomain.Unload by removing superfluous finalization logic which uses Dispatcher.