[Pom] Fix some versions to avoid a bug in latest EMF
[Meta] Add support for feature type
[Runtime] Add new APIs

IObjectDifferential.getObject() is replaced by getObjectUri() which returns a
uri string.

Uri strings are now stored instead of objects in value differentials and the
IValueDifferential.getKind() method returns the kind of value (DATA, OBJECT,
FUNCTION)

IObjectDifferential.getEnclosingValueDifferential() is not yet implemented.