Move ObjectMetaMethod roles to a location usable by the client.
Expose method type to the client.

This requires custom stream operators for serialization. Make use of this
in the property widget, makes the context menu work in the client.
unused
Factor out SafeArgument for re-use and make it actually safe.
Register an object locally as well.

Enables code that is shared between client and server to work, as well as
the in-process UI.
Relay a signal to local subscribers too.

Also, clean up the signal name type and prepare a bit for supporting
arguments.
Add some more sanity checks.