o IvrSipRequest/IvrSipReply python objects need to destroy the underlying c++ object, if they own them (so not for dlg.invite_req, which is the original c++ object owned by the AmSession)
o IvrSipRequest/IvrSipReply python objects need to be DECREFd after calling the onSipRequest/onSipReply methods to free them
git-svn-id: http://svn.berlios.de/svnroot/repos/sems/trunk@1356 8eb893ce-cfd4-0310-b710-fb5ebe64c474