MARTE — TimedDomain stereotype

Resolution of issue 12414 introduced two base metaclasses for
stereotype Clock (InstanceSpecification and Property).
The TimedDomain stereotype has to be changed to support the case of
Clock being a Property extension.
The OCL rule number 1 has also to be updated.

Change the metaclass of TimedDomain from Package to Namespace in Figure
9.26. Also change Extensions of TimedDomain (9.3.2.5). No need to change
OCL rule for this issue because there is no ocl rule associated with
TimedDomain, but see issue 12498 for indirect change.