Tighten the generic CTOR signature.
Fixes #184 Provides traceable versions of Dispatcher, EventRouter, and Filter so that the path of an event through the dispatching and routing system can be traced. By configuring the component with the `traceEventPath()` spec method, the standard components are wrapped with versions that will trace calls to those methods before invoking the delegate method (and in the case of the Filter implementation, after the filter as well). This should aid in debugging an application by showing what consumers get selected (if any) for a given key. In order to see the tracing in the log, however, the log configuration has to be set to TRACE level in addition to using the spec method.