fix userlist presence tracking; "version" command on all services

fix userlist presence tracking; "version" command on all services

* Change scan_handle_presence() to scan_user_presence(), since we always
  have the userData* at the caller site.

* Make handle_auth() respect user suspensions.

* In handle_part(), let scan_user_presence() update "seen" time.

* Make ChanServ adduser command take arguments in the "expected" order
  ("!adduser target level", not "!adduser level target")

* Add the "version" command to all built-in services
git-archimport-id: srvx@srvx.net--2004-srvx/srvx--devo--1.3--patch-7