Merge branch 'openssl_no_ec' of https://github.com/yuki-kodama/nghttp2 into yuki-kodama-openssl_no_ec

The overall meaning is the same. I added a paragraph to introduce nghttp2_hd_inflate_hd(), and added an explanation of using NGHTTP2_NV_FLAG_NO_INDEX for security sensitive headers.

This fixes 2 things:
1. potential busy loop
2. disabling ticket is not working after resumption

Merge branch 'reword-client-tutorial' of https://github.com/skip2/nghttp2 into skip2-reword-client-tutorial

The overall meaning of the tutorial is the same. I added text describing frame types where it helps explain the callbacks better, e.g. introducing the HEADERS frame before on_header_callback().

Also fixed a couple of typos:
- Fixed ``reacb`` typo to ``readcb``
- Added parens to some functions, e.g. ``on_frame_recv_callback`` => ``on_frame_recv_callback()``