do not catch KeyboardInterrupt, let's see stacktraces for now

darcs-hash:20081118074723-b2873-e572c2df636e4d467f2eee472f295855689082ad
sip_msrp_client.py: don't call main in a new greenlet, that does not seem to help with anything

darcs-hash:20081118074808-b2873-d32aa79264785cac9a11d51a424a25ff50dd5f4c