Missing support for ref- and out args for sync calls

[crystalgreen]

Async calls don't support ref- or out arguments but synchronous calls do. But this doesn't work in DispatchProxyAsync.

When calling via Invoke, those arg types should be supported but I get an exception. The original DispatchProxy does support it.

See my example on dotnetfiddle. Also try only out- args or only ref-args.