* riece-user.el: Require 'riece-lru.

* riece-user.el: Require 'riece-lru.
(riece-find-user): Increase priority of given username in
riece-user-lru.
(riece-forget-user): Remove given username from riece-user-lru.
(riece-rename-user): Rename given username in riece-user-lru.
(riece-get-user): Register given username in riece-user-lru (if
is being added to riece-user-obarray.)

* riece-server.el: Require 'riece-lru.
(riece-reset-process-buffer): Initialize riece-user-lru.

* riece-options.el (riece-user-lru-max-size): New user option.
* riece-misc.el: Require 'riece-lru.
(riece-get-users-on-server): Get usernames from riece-user-lru.

* riece-globals.el (riece-user-lru): New variable.
* COMPILE (riece-modules): Added riece-lru.

* riece-lru.el: New file.