Fixes to rfc7230:

fix #1435, fix #1438

* Example and test can be built on msvc v141 15.9.6
  using /std:c++17 and BOOST_BEAST_USE_STD_STRING_VIEW.

* changed string_view.to_string() to std:string(string_view),
  awaiting availability of Library Fundamentals TS here.

* Reactivated relevant tests to param_list. #ifdef 0 test
  exhibited same assertion failed error in debug mode.
  Now fixed in DEBUG on msvc v141 15.9.6 with
  BOOST_BEAST_USE_STD_STRING_VIEW and /std:c++17.

* Looked up http paramters (transfer-encoding, etc.)
  and changed tests as well as fixing comment to
  match specs.

include/boost/beast/http/impl/rfc7230.ipp

@@ -316,7 +316,7 @@ increment()
         param-list  = *( OWS ";" OWS param )
         param       = token OWS "=" OWS ( token / quoted-string )
 
-        chunked;a=b;i=j,gzip;windowBits=12
+        chunked;a=b;i=j;gzip;windowBits=12
         x,y
         ,,,,,chameleon
     */
@@ -350,6 +350,8 @@ increment()
             }
             v_.first = string_view{&*p0,
                 static_cast<std::size_t>(it_ - p0)};
+			if (it_ == last_) 
+				return;
             detail::param_iter pi;
             pi.it = it_;
             pi.first = it_;