Allow multiple controllers #29
Description
It could be useful to allow multiple CLs to connect to the /canonical endpoint.
Currently this is possible, but it won't work particularly well if the CLs send conflicting updates. It's basically the same as if the controlling CLs were directly connected the EL.
Instead, Eleel could act as a mediator, detecting conflicts and preventing them from reaching the EL. The hard part would be tracking which CL to follow in the event of a conflict. This requires some state beyond just "which CL sent me an update first", which would have the EL re-orging all over the place.