Errors and the introspection format

[Havoc Pennington]

Hi,

Possibly the NoReply annotation should have been GLib.NoReply, and
separately we should have a Qt.Async to match the DCOP-compat kind of
feature done in Qt bindings which is slightly different; this would also
help clarify that NoReply is just about bindings and code generation,
not about any intrinsic property of an interface or the wire protocol.

Make sense?

Havoc