At the moment this makes the type as well as the setter/getter available
through the meta-call as well as the ability to register observers and
bindings. Only QProperty members that are annotated with
Q_PROPERTY(type name) are made public through the meta-object.
Change-Id: I16b98fd318122c722b85ce61e39975284e0c2404
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>