Implement a chunked reader (not used yet).
Automatic comma-separated-list header values.
Correct Connection to be a list and test it.

Connection uses 1#(connection-token), so Connection wasn't correct;
it needed to be ~[Connection].
Make everything build.

Still various things that won't work correctly, especially tests.
Fix compile errors with fresh Rust build.

Thanks to @am0d for the patch.
Fixes #3.