nsf.c: - dont't use the default of a invocation parameter in "configure" when the object is already initialized. The default is in general only used when the parameter is not specified. We do not want e.g. superclass to be reset to ::nx::Object, when configure is called on a class without arguments. - extended regression test
nsf.c: - factored out ParameterMethodForwardDispatch() to call a parameter method defined as a forwarder the smae way from "configure" and "cget" - extended regression test