This was XEP-0237, but is now part of RFC 6121.
Roster backends should now expose two additional methods:
version(jid):
Return the version of the given JID's roster.
set_version(jid, version):
Update the version of the given JID's roster.
A new state field will be passed to the backend if an item
has been marked for removal. This is 'removed' which will
be set to True.
As part of adding this feature:
- fixed bug in update_caps() not assigning verstrings
- fixed xep_0004 typo
- can now use None as a roster key which will map to boundjid.bare
- fixed using JID objects in disco node handlers
- fixed failing test related to get_roster
Several of these bugs I've fixed before, so I either didn't push them
earlier, or I clobbered something when merging. *shrug*
Can now use len(self.client_roster) to get the number of JIDs in
the roster, and self.client_roster.groups() to get a dict of
groups and the JIDs in those groups.
