Update submodules: plugins (new commits)

plugins:
    c33feee Chris Smith <chris@dmdirc.com>
            Introduce a DialogProvider.

            This fixes the issues with injection of dialogs and the behaviour of @Singleton.

            Move the swing injection related classes into a new package (a new DialogModule
            will follow shortly to make use of the DialogProvider).

            Also introduce a SwingPreconditions class for asserting method calls are made
            on/off the EDT.

            Gerrit: http://gerrit.dmdirc.com/3044

Change-Id: I1f74671b7881ecffdcf261052dfea4576237080b