Remove some dead code.

Change-Id: Ib3f12415ce518c7f2c735667c8a00a3970e75ad3
Reviewed-on: http://gerrit.dmdirc.com/2903
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Automatic-Compile: DMDirc Build Manager
Update submodules: plugins (new commits)

plugins:
    26c471a Chris Smith <chris@dmdirc.com>
            Remove some dead code.

            Gerrit: http://gerrit.dmdirc.com/2904

Change-Id: I022bbff86fe359c559ddf76469927e797815174e