Added comment about tests of o= SDP line in reINVITEs

Ignore-this: 1f1c3f7f164599ddcbf66ed5080f3374

darcs-hash:20091021170154-1e3d8-9f45fdecf1a765a18a388b6c59a2a672d93ea2c3
Renamed Canceled with Session Canceled

darcs-hash:20091025175046-58252-2048bf0ea628a0b5319da70a2e495a95c6450254