Allow kicking/banning/muting/unmuting/deafening and undeafening through
the UserListView right-click menu (if permissions are sufficient).
Support for banning, kicking, and muting were added to the XMPP add-on―
deafening isn't supported, so is left out.
UserListView and UserItem were added as the backbone of the user-list,
and the (currently unused) Caya message CAYA_SEND_INVITE was established
for inviting users to rooms.
Some menus were reworked (e.g., pop-ups of the RosterListView) or
generally tweaked to be more sensical or consistent.
Jaidyn Ann