Direct edit of constraints should allow to access elements in the ancestor namespaces

[gdaniel]

The following SysML model is valid:

part a {
    attribute b;
}

requirement c {
    require constraint {a.b >= 10}
}

Even if a isn't the subject of c. Resolving a name inside a constraint shouldn't be different than in other places (see KerML 8.2.3.5 for the details on how names are resolved).