merge with crew

adding local_hostname option to smtp configuration

Respect "Connection: close" headers sent by HTTP clients. A HTTP client can indicate that it doesn't support (or doesn't want) persistent connections by sending this header. This not only makes the server more compliant with the RFC, but also reduces the run time of test-http-proxy when run with python 2.3 from ~125s to ~5s (it doesn't affect it with python 2.4, which was already ~5s).

allow use of extensions in python hooks extensions are loaded with hgext_ prefix, try to use them if the module is not found in the normal path