Update submodules: plugins (new commits)

plugins:
    e46d8e6 Greg Holmes <greg@dmdirc.com>
            Hack prefs dialog into working.

            For the minute this means the prefs dialog no longer
            saves state, it also means there may be some layout
            changes with the height loss and parenting change for
            sub dialogs launched from preferences settings.

            Gerrit: http://gerrit.dmdirc.com/3071

Change-Id: Id8cc598c8466c325faf1d7af1d0a20e208b681cd