• switching to nghttp2 v1.0., compilation + linkage with nghttp2 v0.7. will
  not work any more as there have been changes in nghttp2's API. The sandbox
  builds against v1.0.2 and also pulls curl 7.43.0 which did the same version
  switch.
• keeping support for h2-16/h2-14 ALPN identifiers until a 1.0 release
• varying h2 support (on|off) among virtual hosts on the same port is now
  possible and should work correctly.
• improved mod_ssl alpn patch to correctly select the proper virtual host
  even if the SSL library invokes SNI after ALPN callbacks.
• Disabled NPN support in sandbox built. The patch for httpd 2.4.x is still
  there, but no longer applied.
• KNOWN ISSUE: when using mpm_event, the error
  "error scoreboard is full, not at MaxRequestWorkers"
  sometimes happens. Under investigation. mpm_worker ist stable and recommended
  for now.