QVT — Revise the encoding of primitive domains

Primitive domains are simpler than other relation domains
since they do are not dependent on a given typed model
(primitive types are available to all metamodels) and there
is no need to refer to a template expression.
In QVTBase package, the multiplicity of Domain::typedModel
should be '0..1' instead of '1' to avoid an arbitrary assignment
to model typed model for the primitive diomain. In addition
the multiplicity of RelationDomain-Pattern association should
be changed to 0..1.

(1) In Section 7.11.1.3, replace "typedModel: TypedModel [1]"
by "typedModel: TypedModel [0..1]"
In figure 7.4 change the corresponding multiplicity.

(2) In 7.11.3.2, replace "/typedModel: TypedModel [1] (from Domain)"
by "/typedModel: TypedModel [0..1] (from Domain)"
and replace "pattern: DomainPattern [1]

"
Make the corresponding change in figure 7.7.