mod_h2 v0.6.0

• new config options "H2HackMpmEvent (On|Off) that enables a hack to make
  internal connection work with the mpm_event module. Has no effect if other
  mpm modules have been configured. Defaults to "On"."
• new config option "H2SerializeHeaders (On|Off)" that determines if request
  response headers should be serialized/parsed when converting from HTTP/2 to
  httpd's internal HTTP/1 processing or request_recs are manipulated directly.
  "Off" is default, "On" gives better compatibility.
• ./configure --enable-werror enables all sorts of compiler diagnostics, if
  the chosen compiler supports them
• merged pull request with compiler warning fixes by LPardue and @samhurst
  (Thanks!)
• fiddling around with task/worker assignments to use the global h2_workers
  lock less, giving better parallelism
• upgrading sandbox to nghttp2 0.7.15