HTTP/2 C library and tools

Nghttp2 v1.18.1

We have released nghttp2 v1.18.1.

This release fixes several bugs in nghttpx proxy server. Since v1.18.0 release, dynamic DNS feature has been added to nghttpx. This release fixes these DNS related bugs. User reported that nghttpx exited with assertion error in libev code when DNS was enabled. After investigating it, it turned out that this bug had existed well before DNS was added, but enabling DNS helped to trigger the bug.