Refactor header status, reason, and target (API Change):

* header::result is a family of functions to replace header::status

* header interface now uses status enum and also ints

* reason-phrase is no longer stored unless the user explicitly
  requests it.

* When serializing, the standard reason is used for the
  corresponding status code unless the user has changed it.

include/beast/http/impl/fields.ipp

@@ -230,8 +230,7 @@ erase(string_view name)
 template<class Allocator>
 void
 basic_fields<Allocator>::
-insert(string_view name,
-    string_view value)
+insert(string_view name, string_view value)
 {
     value = detail::trim(value);
     auto const p = alloc_traits::allocate(this->member(), 1);
@@ -243,33 +242,13 @@ insert(string_view name,
 template<class Allocator>
 void
 basic_fields<Allocator>::
-replace(string_view name,
-    string_view value)
+replace(string_view name, string_view value)
 {
     value = detail::trim(value);
     erase(name);
     insert(name, value);
 }
 
-template<class Allocator>
-string_view
-basic_fields<Allocator>::
-method_string() const
-{
-    return (*this)[":method"];
-}
-
-template<class Allocator>
-void
-basic_fields<Allocator>::
-method_string(string_view s)
-{
-    if(s.empty())
-        this->erase(":method");
-    else
-        this->replace(":method", s);
-}
-
 } // http
 } // beast