R__GetQualifiedName now leverages GetFullyQualifiedTypeName

There is one mechanism to get the "right" name for types now.
Only exception are of course namespaces.
I took the opportunity to add comments, shuffle code for an
increased clarity.

half of the work done

all issues solved except the NamespaceDecl and NamedDecl.

Compilation ok, segfault for Type to QualType

Fix flacky transformation from Type to QualType