Add EmacsKeys plugin.

A very simple non-intrusive plugin. Adds a bunch of actions typical emacs user
would expect. Doesn't contain any default key bindings.

Change-Id: Ib30fb46c577e2fdfd4c704e7f4eee7ee27a53c29
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>
Reviewed-by: hjk <hjk121@nokiamail.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>