in chunked encoding, read the exact number of bytes required.
in chunked encoding, read the exact number of bytes required.

Closes #3

edwintorok/ocaml-cohttp,marklrh/ocaml-cohttp,mor1/ocaml-cohttp,edwintorok/ocaml-cohttp,inhabitedtype/ocaml-cohttp,fdopen/ocaml-cohttp,fdopen/ocaml-cohttp,mor1/ocaml-cohttp,Drup/ocaml-cohttp,Drup/ocaml-cohttp,marklrh/ocaml-cohttp,edwintorok/ocaml-cohttp,dsheets/ocaml-cohttp,dsheets/ocaml-cohttp,inhabitedtype/ocaml-cohttp,fdopen/ocaml-cohttp,Drup/ocaml-cohttp,inhabitedtype/ocaml-cohttp,marklrh/ocaml-cohttp,dsheets/ocaml-cohttp,mor1/ocaml-cohttp