EventContainer scope event removal

[NeonDaniel]

EventContainer already tracks events and callbacks added via the container; rather than removing all listeners on remove, it should remove specific callbacks that it manages.

[NeonDaniel]

Current behavior (after removing specific events/handlers):

        # Because of function wrappers, the emitter doesn't always directly
        # hold the _handler function, it sometimes holds something like
        # 'wrapper(_handler)'.  So a call like:
        #     self.bus.remove(_name, _handler)
        # will not find it, leaving an event handler with that name left behind
        # waiting to fire if it is ever re-installed and triggered.
        # Remove all handlers with the given name, regardless of handler.
        if removed:
            self.bus.remove_all_listeners(name)

A better implementation would need to keep track of wrapped functions to more precisely remove only the handlers managed by this container