renamed InvitationBuffer's 'me' and 'other' attributes to 'local_uri' and 'remote_uri'; added 'call_id' attribute

darcs-hash:20090121091640-b2873-547d6d4b0504d23d4a577b418b0f60ae759b99a1
sip_im_session: don't print the traceback if accept_incoming_loop was killed

darcs-hash:20090121091926-b2873-abfe0debd63227666def111de6b7224971f290a0