Update submodules: plugins (new commits)

plugins:
    e118b28 Chris Smith <chris@dmdirc.com>
            Add preferences meta-data.

            This is a conversion of all the current swing pref settings to
            a new meta-data format. The plan is for the core/plugin system
            to be able to parse this and generate the necessary model for
            the prefs system.

            Gerrit: http://gerrit.dmdirc.com/3321

Change-Id: I38182dd2aefcf62cdaa328204af2cb64f3c54687