check_session.c: added more CANCEL cases
check_session.c: added more CANCEL cases

2.2.5 - CANCEL glare test case (failing)
2.2.6 - Simple nua UAS CANCEL case
2.2.7 - RFC 2543 client CANCELing, nua as UAS

darcs-hash:20080910143735-db55f-aa7c5727a3ebf77e6ae98bafdecde491235703d1.gz

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