*) mod_ssl: for all ssl_engine_vars.c lookups, fall back to master connection
   if conn_rec itself holds no valid SSLConnRec*. Fixes PR58666.
   [Stefan Eissing]

*) mod_http2: connection level window for flow control is set to protocol
   maximum of 2GB-1, preventing window exhaustion when sending data on many
   streams with higher cumulative window size.
   Reducing write frequency unless push promises need to be flushed.
   [Stefan Eissing]

*) mod_http2: required minimum version of libnghttp2 is 1.2.1
   [Stefan Eissing]

*) mod_proxy_fdpass: Fix AH01153 error when using the default configuration.
   In earlier version of httpd, you can explicitelly set the 'flusher' parameter
   to 'flush' as a workaround. (i.e. flusher=flush)
   Add documentation for the 'flusher' parameter when defining a proxy worker.
   [Christophe Jaillet]

*) mod_ssl: For the "SSLStaplingReturnResponderErrors off" case, make sure
   to only staple responses with certificate status "good". [Kaspar Brand]

*) mod_http2: new directive 'H2PushPriority' to allow priority specifications
   on server pushed streams according to their content-type.
   [Stefan Eissing]

*) mod_http2: fixes crash on connection abort for a busy connection.
   fixes crash on a request that did not produce any response.
   [Stefan Eissing]

*) mod_http2: trailers are sent after reponse body if set in request_rec
   trailers_out before the end-of-request bucket is sent through the
   output filters. [Stefan Eissing]

*) mod_http2: incoming trailers (headers after request body) are properly
   forwarded to the processing engine. [Stefan Eissing]

*) mod_http2: new directive 'H2Push' to en-/disable HTTP/2 server
   pushes a server/virtual host. Pushes are initiated by the presence
   of 'Link:' headers with relation 'preload' on a response. [Stefan Eissing]

*) mod_http2: write performance of http2 improved for larger resources,
   especially static files. [Stefan Eissing]

*) core: if the first HTTP/1.1 request on a connection goes to a server that
   prefers different protocols, these protocols are announced in a Upgrade:
   header on the response, mentioning the preferred protocols.
   [Stefan Eissing]

*) mod_http2: new directives 'H2TLSWarmUpSize' and 'H2TLSCoolDownSecs'
   to control TLS record sizes during connection lifetime.
   [Stefan Eissing]

*) mod_http2: new directive 'H2ModernTLSOnly' to enforce security
   requirements of RFC 7540 on TLS connections. [Stefan Eissing]

*) core: add ap_get_protocol_upgrades() to retrieve the list of protocols
   that a client could possibly upgrade to. Use in first request on a
   connection to announce protocol choices. [Stefan Eissing]

*) mod_http2: reworked deallocation on connection shutdown and worker
   abort. Separate parent pool for all workers. worker threads are joined
   on planned worker shutdown. [Yann Ylavic, Stefan Eissing]

*) mod_ssl: when receiving requests for other virtual hosts than the handshake
   server, the SSL parameters are checked for equality. With equal
   configuration, requests are passed for processing. Any change will trigger
   the old behaviour of "421 Misdirected Request".
   SSL now remembers the cipher suite that was used for the last handshake.
   This is compared against for any vhost/directory cipher specification.
   Detailed examination of renegotiation is only done when these do not
   match.
   Renegotiation is 403ed when a master connection is present. Exact reason
   is given additionally in a request note. [Stefan Eissing]

*) core: Fix scoreboard crash (SIGBUS) on hardware requiring strict 64bit
   alignment (SPARC64, PPC64).  [Yann Ylavic]

*) mod_cache: Accept HT (Horizontal Tab) when parsing cache related header
   fields as described in RFC7230. [Christophe Jaillet]

*) core/util_script: making REDIRECT_URL a full URL is now opt-in
   via new 'QualifyRedirectURL' directive.

*) core: Limit to ten the number of tolerated empty lines between request,
   and consume them before the pipelining check to avoid possible response
   delay when reading the next request without flushing.  [Yann Ylavic]

*) mod_ssl: Extend expression parser registration to support ssl variables
   in any expression using mod_rewrite syntax "%{SSL:VARNAME}" or function
   syntax "ssl(VARNAME)". [Rainer Jung]