This is a streaming HTTP header parser. All it currently does is detect
the end of headers. This will be a non-allocating parser where one can
bring supply their own buffer if they want to handle custom headers.
This commit also improves std.http.Client to not return the HTTP headers
with the read functions.
I want to take the design of this in a different direction. I think this
abstraction is too high level. I want to start bottom-up.
std-lib-orphanage commit 179ae67d61455758d71037434704fd4a17a635a9
