Introduce a ConnectionManager.

Remove most references to Server.

Change-Id: I8888522d58ff4d332c4a477702442c29a82d12ff
Depends-On: Ic0e6e5f95adc30e773945c95e73d321d589503d2
Reviewed-on: http://gerrit.dmdirc.com/3872
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Update submodules: plugins (new commits)

plugins:
    8cc02bb Chris Smith <chris@dmdirc.com>
            Use ConnectionManager.

            Depends-On: I8888522d58ff4d332c4a477702442c29a82d12ff
            Gerrit: http://gerrit.dmdirc.com/3871

Change-Id: I1b07a3cbed27b892d4ec98bdd0e71b3aaa80d143