Get rid of _$loginSubmitOn_old
Get rid of _$loginSubmitOn_old

Also fire login/out callbacks for .dw-login-on-mouseenter (not only for -on-click),
and rename registerEventHandlers() to registerEventHandlersFireLoginOut().

debiki/debiki-server-old,debiki/debiki-server-old,debiki/debiki-server-old,debiki/debiki-server-old