*) mod_http2: v2.0.15 with the following fixes and improvements
     - New directive 'H2EarlyHint name value' to add headers to a response,
       picked up already when a "103 Early Hints" response is sent. 'name' and
       'value' must comply to the HTTP field restrictions.
       This directive can be repeated several times and header fields of the
       same names add. Sending a 'Link' header with 'preload' relation will
       also cause a HTTP/2 PUSH if enabled and supported by the client.
     - Fixed an issue where requests were not logged and accounted in a timely
       fashion when the connection returns to "keepalive" handling, e.g. when
       the request served was the last outstanding one.
       This led to late appearance in access logs with wrong duration times
       reported.
     - Accurately report the bytes sent for a request in the '%O' Log format.
       This addresses #203, a long outstanding issue where mod_h2 has reported
       numbers over-eagerly from internal buffering and not what has actually
       been placed on the connection.
       The numbers are now the same with and without H2CopyFiles enabled.
     [Stefan Eissing]