some sites do redirects or interrupt them based on cookies.
Add support for cookies on redirects for the simple_httpclient
Cookies should only be sent if the domains match (among other requirements). Trying to emulate browser policies here seems tricky, so any cookie support should be opt-in (and perhaps based on a pluggable policy object; see the standard library's cookielib for example).
Please add a test for this change (and fix the tests that are failing on python 3).