QVT — Entry operations in operational definitions

For models that have a well identified "root" element and type,
it makes sence to designate a mapping operation on the root
type to be the entry of the transformation. Currently this is not
possible.

Suggestion:
Replace the 'OperationalTransformation::entry : EntryOperation'
association by a more general 'Module::entry : Operation'

In Section 8.2.1.1 (OperationalTransformation),
remove the association "entry : EntryOperation [0..1]" and
in Section 8.2.1.3 (Module) inserts the association "entry : Operation [0..1]".
In Figure 8.1, make the corresponding move of the 'entry' link.