Doc: Remove all references to Qt Simulator

Simulator Qt is not distributed any more and plugins for
the platforms that used it are no longer delivered with
Qt Creator. If someone is still using Qt Simulator, they
will have the documentation delivered with it.

Change-Id: Ifc0cc7fa875e29b0cdff89772cf0f41d52a05f35
Reviewed-by: Rainer Keller <rainer.keller@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>