Update submodules: plugins (new commits)

plugins:
    d81b9c7 Greg Holmes <greg@dmdirc.com>
            Fix issues with duration editor.

            Add a DMDirc icon instead of java icon for editor window.
            Stop doubling duration preferences.

            Fixes-Issue: CLIENT-458
            Fixes-Issue: CLIENT-459
            Gerrit: http://gerrit.dmdirc.com/3207

Change-Id: I3379983d08f91cc1a0eb10ee49f93a0e0b6b867e