Update submodules: plugins (new commits)

plugins:
    e1a4293 Chris Smith <chris@dmdirc.com>
            Remove static ColourManager calls.

            Remove many unused constructors from swing colour components.

            Gerrit: http://gerrit.dmdirc.com/2824

Change-Id: I44f7547cdd740bb1c78d6d8fc372e889d6c9b2b5