The "socks" feature has been removed for a while now, the optional
dependency on the "socks" crate commented out.
The code for actually providing the socks feature was, however, still
mostly present, if a bit out of date.
This commit re-adds the socks feature using the tokio-socks (instead of
socks) crate.
Closes#620
If no proxies are configured for a client, the environment (system) will
be inspected automatically to set up proxies.
Configuring a `Proxy` on a client or calling `no_proxy` will disable the
use of the automatic system proxy.
Closes#403
- The `Error`'s kind is a now a set of variants depending on the context
of when an error could occur.
- If another error was the cause, it is now always the `source`.
Along with the `is_*` methods, this should help in understanding *when*
a certain error occurred. For example, an error setting the TLS
certificates will return a builder error, with the TLS error as the
source. This should help differentiate from a TLS error that happens
when connecting to a server.
It also makes the internal code less dependent on all the exact
dependencies that can be enabled or disabled.
