Fixes, fail testing:

Core:

* Test buffer_cat iterator move members

HTTP:

* Fixed yield / resume in writer
* Fixed message serialization with chunked encoding

* Test yield / resume in writer
* Test all conditional branches during message serialization
* Test chunked encoding
* Increase coverage on parse_error
* Add parse_error::general

WebSocket:

* Add error::general
* Increase coverage in error

include/beast/websocket/impl/stream.ipp

@@ -861,6 +861,7 @@ build_response(http::request_v1<Body, Headers> const& req)
             res.version = req.version;
             res.body = text;
             // VFALCO TODO respect keep-alive here
+            prepare(res);
             return res;
         };
     if(req.version < 11)