Stenberg: Dropping hyper

Curl maintainer Daniel Stenberg announcesthat the curl project will be dropping hyper, its experimental HTTP backendwritten in Rust, due to lack of developer interest.

While the experiment itself is deemed a failure, I think we learnedfrom it and improved curl in the process. We had to rethink andreassess several implementation details when we aligned HTTPbehavior with hyper. libcurl parses and handles HTTP stricternow. Better.