Replaced HandlerQueue usage with interface; clarified names of queue related synchronization event objects.
Added interface for IHandlerRegistry.
Renamed some handler dispatcher classes to schedulers, as they don't dispatch (execute) handlers but schedule (queue for execution) them.
Renamed DeserializeRequest to DeserializeRequestBody.
Merged AsyncQuery and AsyncCommand into Query and Command.
Made Dispatch method non-generic as it was only used with object type parameter.