Better subscription path API support. Should support us better moving
forward.
Note that this kills the server-hook. It will be replaced with a
link-view shortly.
Also re-orders the comment paths to have URL first, which is easier to
handle and also seems more correct wrt the behavior you might want in
the web extension and similar use cases.
Instead of providing a (unit path), allows for (list path), which better
supports the "update to path and subpath cases".
For example, if /things wants updates about everything, and
/things/specific wants updates about the specific thing, they'll both
need to receive a %fact when the specific thing changes.
Previously, these would have been two separate moves. Now, gall handles
the multi-targeting for you.
This resolves a number of issues that were keeping communications with
foreign ships from working.
- there was no link-update mark
- there was no +on-arvo handling in link-listen-hook
- link-listen-hook was subscribing to the non-existent "link-hook"
- link-proxy-hook permission check was looking at a wrong path
Also makes link-listen-hook aware that subscriptions might get rejected
because of permissions, so that it ignores failed subscriptions instead
of being loud about it.
Stores URLs and their titles for the local ship. Can listen to
"submissions" on foreign ships.
Has a primitive perspective on groups, treating them as
always-interesting. Auto-subscribes to all ships in all groups.
Foreign communications untested.
