mod_vcard_muc: Pass room object around instead of JID, hopefully fixing traceback More efficient to pass the object around instead of using the JID and looking up the object when needed. It seems in some (undetermined) cases get_room_from_jid(room.jid) is nil.

This module lets you block connections to any remote servers not on a
whitelist.

``` {.lua}
s2s_whitelist = {
    "example.org",
}
```