Various fixes, warnings:

* Fix sig_wait
* Fix websocket strict aliasing warning
* Fix invokable strict aliasing
* Silence fread warning in examples
* Silence integer conversion warnings
* Build parser-bench as test
* Disable unused variable warning for asio:
    Caused by static variables declared in <boost/asio/error.hpp>
    No known workaround.

include/beast/http/parser.hpp

@@ -118,7 +118,7 @@ private:
                 }
                 return false;
             };
-        while(false)
+        do
         {
             if(m("DELETE",     method_t::http_delete))
                 break;
@@ -187,6 +187,7 @@ private:
             if(m("UNLINK",     method_t::http_unlink))
                 break;
         }
+        while(false);
 
         m_.url = std::move(this->uri_);