[INCOMPATIBLE CHANGES]
- The 'proxy' attribute no longer takes precedence over the
'http_proxy' environment variable. With the addition of http_proxy
and https_proxy attributes (and corresponding environment variable
defaults), the legacy 'proxy' attribute now maps to the
all_proxy/ALL_PROXY environment variable and only takes effect when
other proxy attributes are not defined.
[ADDED]
Added support for Basic authorization with proxies
Added support for https proxies via CONNECT