* riece-identity.el (riece-completing-read-identity): Pass 6th &

* riece-identity.el (riece-completing-read-identity): Pass 6th &
7th arguments to completing-read.

* riece-commands.el (riece-command-part): Use 6th argument DEFAULT
of riece-completing-read-identity.

* riece-handle.el (riece-handle-invite-message): Fix parsing of
parameters.

* riece-display.el (riece-update-channel-list-buffer): Don't clear
riece-channel-list-changed.
(riece-update-buffers): Clear it.