Update submodules: plugins (new commits)

plugins:
    f3c78b8 Greg Holmes <greg@dmdirc.com>
            Disable edit/delete buttons when no nickname is selected.

            Fixes-Issue: CLIENT-508
            Gerrit: http://gerrit.dmdirc.com/3404

Change-Id: I08bdec0d6515e9109be2d2e0ed1d5eaf85ac6031