vweb: add a placeholder for checking route validity at startup

vlib/vweb/vweb.v

@@ -199,6 +199,11 @@ pub fn run_app<T>(mut app T, port int) {
 	l := net.listen(port) or { panic('failed to listen') }
 	app.vweb = Context{}
 	app.init_once()
+	$for method in T.methods {
+		$if method.return_type is Result {
+			// check routes for validity
+		}
+	}        
 	//app.reset()
 	for {
 		conn := l.accept() or { panic('accept() failed') }