Update submodules: plugins (new commits)

plugins:
    0fe941d Chris Smith <chris@dmdirc.com>
            Use WindowProviders/factories for all windows.

            Remove the legacy code, which was used in far fewer places than I thought.

            Gerrit: http://gerrit.dmdirc.com/3063

Change-Id: Ie8bbb24653cfd6711f7fa0e27ab842cacc14fb46