GitLab

Feature events rebased

See merge request !1

Implements PacketInEvent, MultipartReply, and MeterMod events, triggered
in Controller.

Only MultipartReply needs to be handled, in Stats_manager.

We make the Controller a "friend" of Subscription: this way, it has
access to private fields of Subscription and can trigger an event. We
make the actual connection private so that apps *cannot* trigger it.