Like related events should be produced in reaction to rating events

Like feature is based on rating, so saving a like actually means saving a rating.

Unfortunately, the current design does not follow the same logic for events. Like events are produced totally independently of rating events, which makes it quite a pain to implement generic manipulation of ratings (for example, if you copy a rating that happen to be a like it will be totally invisible to the like system to invalidate various caches).

It also affects the update of average likes but even worst since it's not even listening to like events.