Calling constructors

[djungelorm]

Add support for calling constructors. For example:

conn = krpc.connect()
vessel = conn.space_center.Vessel("foo")

[KRPCClass(Service="SpaceCenter")]
class Vessel {
  [KRPCConstructor]
  Vessel (string name) { ... }
}

This should be relatively straightforward. The service definitions just contain an extra procedure call, that looks like a static class method, whose arguments are the same as the constructor, and return type is the class.

Generated client stubs would contain a call to this procedure in the constructor, and store the returned object id in the class instance.

Most of the work is in updating the clients.