lab 5: shared: added EventHandlerWithContext interface, made
EventChannelEventHandler extend it, and added SingleEventTypeEventHandlerWith-
Context; need to later replace the EventChannel version with this since it
is more generic. taja: updated EventDispatchController to use the newly
added SingleEventTypeEventHandlerWithContext with HttpServletRequest as
the context.
lab 5: shared: added method to EventDispatcher to handle dispatchin to
EventHandlerWithContext objects with generic context parameters. taja: updated
EventDispatchController to use EventHandlerWithContext<HttpServletRequest>
handler types, and use EventDispatcher.dispathEventWithContext.
lab 5: taja: EventDispatchController: generate the analysis URL from the
HttpServletRequest context argument, renamed the attribute 'rendering_query_-
string' to 'analysis_url'.