Slot trace reform: - redesign of slot interface of traces from * variables contains cmds and variable references to * slot specific methods with the same interface as slot-setters - new: * specify flag "-trace" with a list of values "get", "set", "default" * when flag is set, a trace will be registered calling methods value=get obj variable value=set obj variable value value=default obj variable on the slot (actually the first two are identical with the methods used for slot-defined accessors) - updated regression test * new flag "-notrace" for "nsf::var::set" and "nsf::var::get"
