NGHTTP2_CLIENT_CONNECTION_PREFACE has the same content with
NGHTTP2_CLIENT_CONNECTION_HEADER, which is now obsoleted by
NGHTTP2_CLIENT_CONNECTION_PREFACE.
* Use 1 Huffman code table for both request and response
* Remove complicated deflater side table size management
* Add encoding context update
* Fix memory leak in inflater
This happens when deflater local header table is smaller than
inflater header table size. We use the same notation
"**DEALLOCATED**" for such name/values with hdtest programs.
To build extension module, cython is required.
The module is not built with `make` in the top directory.
A user has to run `make build_ext` in python directory.
Currently header compression objects are available for testing.
Tatsuhiro Tsujikawa