message::version is a member function (API Change):

fix #778

* The version data member is replaced with accessor
  member functions.

Actions Required:

* Call member function message::version instead of accessing
  the version member at call sites.

example/http/client/async/http_client_async.cpp

@@ -62,7 +62,7 @@ public:
         char const* target)
     {
         // Set up an HTTP GET request message
-        req_.version = 11;
+        req_.version(11);
         req_.method(http::verb::get);
         req_.target(target);
         req_.set(http::field::host, host);