Also, don't query for MAM messages if the chat room doesn't support it.

allow_non_roster_messaging is false.

Fixes #745

So that when a higher priority resource goes offline, we can fall back to the
right chat status if at the next priority level there are multiple resources.

https://github.com/jcbrand/converse.js/commit/789654d54e7a8c80b35934f526e05ee7802c790f#comments

updates #785

Improve upon the previous implementation.

If the resource with the highest priority goes offline or becomes unavailable,
then the chat status of the contact must fall back to that of the resource with
the next highest priority.

In your example from #785, if the resource with priority 1 goes offline or
becomes unavailable, then in your implementation the chat status would stay at
online, although it must actually go to xa.

The solution is to update the resources attribute on the contact to not just be
an array or strings, but instead to be a map of resources to priorities and
statuses and to use that data structure.

https://greenkeeper.io/

So that the occupants list doesn't get wiped.

If it's needed in another plugin, it can simply be `require`'d.

or if the room is members-only and the user is not the owner.

if you're allowed to see it.

Otherwise re-login hangs after authfail.