url: support auth.cookiesfile for adding cookies to HTTP requests Mercurial can't currently send cookies as part of HTTP requests. Some authentication systems use cookies. So, it seems like adding support for sending cookies seems like a useful feature. This patch implements support for reading cookies from a file and automatically sending them as part of the request. We rely on the "cookiejar" Python module to do the heavy lifting of parsing cookies files. We currently only support the Mozilla (really Netscape-era) cookie format. There is another format supported by cookielib and we may want to consider using that, especially since the Netscape cookie parser can't parse ports. It wasn't immediately obvious to me what the format of the other parser is, so I didn't know how to test it. I /think/ it might be literal "Cookie" header values, but I'm not sure. If it is more robust than the Netscape format, we may want to just support it.

httpconnection: allow a global auth.cookiefile config entry This foreshadows support for defining a cookies file.

util: make cookielib module available In preparation for supporting sending cookies on HTTP requests.