Update submodules: plugins (new commits)

plugins:
    e9fcd57 Chris Smith <chris@dmdirc.com>
            Use some more events.

            Remove some deprecated methods in ChannelFrame.

            Gerrit: http://gerrit.dmdirc.com/3249

Change-Id: I93c37b6ab1092ae5a2d4f634e2470817f7cacc26