Added test_sec_ext() for testing security agreement headers.
Added test_sec_ext() for testing security agreement headers.

darcs-hash:20051215121246-65a35-18eee1fb982d33796b5c5de50ed0d99315f2544d.gz

unispeech/sofia-sip,erdincay/sofia-sip,xhook/sofia-sip,BelledonneCommunications/sofia-sip,BelledonneCommunications/sofia-sip,jart/sofia-sip,erdincay/sofia-sip,erdincay/sofia-sip,unispeech/sofia-sip,BelledonneCommunications/sofia-sip,xhook/sofia-sip,xhook/sofia-sip,unispeech/sofia-sip,jart/sofia-sip,jart/sofia-sip,erdincay/sofia-sip,xhook/sofia-sip,unispeech/sofia-sip,BelledonneCommunications/sofia-sip,xhook/sofia-sip