- 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.
"inflate" actually means decompress in the context of DEFLATE. "deflate" reduces the size of something, i.e. compression, and inflate is the opposite, i.e. decompression.
