[sr-dev] registrar method_filtering

if registrar method_filtering param is set, lookup produces -2 and $du is not set if method is not listed in allow header of register request. this is fine with initial requests, but in case of an invite dialog, initial invite may list another set of methods that the ua supports in in-dialog requests. if request uri of in-dialog request is gruu, lookup on it would thus fail and $du is not set if method of the request was not in allow header of register request, but was in allow header of initial invite. in order to solve the problem, my suggestion is that lookup would set $du also when it returns -2. comments? -- juha