Events always pass through these, adding to the stack trace on-crash.
This information is practically never useful, however. Adding !. leaves
these cores out of the traces.
(Re)subscribing gets us a %contacts update, containing the full set of
contacts as it currently exists.
Previously, we would fully delete our local state, only to recreate it
using the data from the update.
Now, we never delete existing data, instead only creating if we don't
have it yet, and adding, removing or recreating contacts if they
changed.
In the future, we'll want an easy way to turn two contacts into an %edit
diff, to let us apply correct semantics to individual contacts, too.
Instead, %bundle and %add if we don't have the group locally yet,
or %add and %remove whatever the difference is between the local group
and the group as specified in the %path update.
In both, we make clear that the wire is always of the /@/group/^ form,
and alias the "group path" portion of the wire for clarity.
For kick, more obviously reuse the same wire, don't reconstruct it.
For watch-nack, only delete from the synced map if the source of the
watch-nack is still relevant. While we don't expect this to be relevant
considering current mode of operation, this does protect us against
strange cases.
Deletion retains its old behavior: can only be done by group owner, and
propagates.
Removing can now always be done by anyone, and works using
link-listen-hook: removing the collections from the set of ones we're
interested in, no longer syncing or showing up in the sidebar.
Instead of going purely off metadata, we now track the collections we're
listening to, and allow the user to remove collections from that list.
This allows us to remove/ignore collections, without mutilating group
assocations locally.
We were taking care not to re-add something to our data store if we
already had it in there, but were still sending out an update
regardless.
With this, we only send out an update if we weren't previously aware
of the content.
