Use char literals instead of codepoint numbers for constants.
Add the Content-Type header.
Improve Accept-Ranges header compliance.
Generate headers::{request, response} with a macro.

This leads to a very significant reduction in duplication.
Use a more robust "header value finished" check.

This won't affect the particular case it's used in now, but will affect
other header values that I'm working on.

This *is* now a destructive function (as noted in the method docs), but
I believe that will normally be what I require. For other cases, there
is still ``self.state == Finished``; it may be safer not to have this in
a method, hence its present removal.
Add HeaderConvertible tests for ~str and uint.
Merge (fixes a couple of minor errors also).
Fix a logic error in reading quoted-string.
Fix compilation from latest changes.
Rename "tests" make rule to "check".

(This is for consistency with Rust.)
Fix test compile errors.
More intelligent "make check" dependencies.
Fix up header tests and HTTP-date bugs.
Fix memstream code.

Rust compiler should have objected, but instead gave junk. Not good.
Add memstream to dependencies in Makefile.
Start implementing Transfer-Encoding: chunked.

Written on a machine without rustc, so this changeset is probably broken
on its own, as usual.
Add accidentally missing transfer_encoding module.
Fix up compile failures with Transfer-Encoding.
Get chunked response writing working.
Fix some Makefile dependency patterns.