This commit fixes the bug that DATA is not consumed if
nghttp2_http_on_data_chunk is failed.  It also simplify the handling
of missing stream in NGHTTP2_IB_READ_DATA state.

This commit documents NGHTTP2_ERR_DATA_EXIST also occurs if HEADERS
has been already attached to stream too.  This commit also fixes
possible assertion error, and now nghttp2_submit_headers() and
nghttp2_submit_response() may return NGHTTP2_ERR_DATA_EXIST.  But we
recommend to use nghttp2_submit_request() and
nghttp2_submit_response(), and using them will avoid this error.

* fix build broken by recent changes
* place all build artifacts to OBJDIR
* explicitly add manifest (VC9/10)
* modernize python bindings creation
* some minor refactoring

Patch from Klaus Ziegler

comment of pushed moved from request to entry array
added stream_id as string to connection element as string