ROADMAP: remove two items already done

   To decide: if we need to bundle parts of the nghttp2 stuff that probably

   won't be shipped by many distros.

- stream properties API

   Provide options for setting priorities and dependencies among the streams

   (easy handles). They are mostly information set for the stream and sent to

   the server so we don't have to add much logic for this.

- server push

   Not exactly clear exactly how to support this API-wise, but by adding

   handles without asking for a resource it could be a way to be prepared to

   receive pushes in case such are sent. We probably need it to still specify

   a URL with host name, port etc but we probably need a special option to

   tell libcurl it is for server push purposes.

- provide option for HTTP/2 "prior knowledge" over clear text

   As it would avoid the roundtrip-heavy Upgrade: procedures when you _know_

2. curl -h output (considered overwhelming to users)

3. we have > 160 command line options, is there a way to redo things to

3. we have > 170 command line options, is there a way to redo things to

   simplify or improve the situation as we are likely to keep adding

   features/options in the future too