Instanciate common attributes everywhere so one can simply use the extend method

link.go

@@ -19,7 +19,10 @@ type Link struct {
 
 // NewLink creates a new Link. It returns a *Link.
 func NewLink(href string) *Link {
-	return &Link{Href: href}
+	return &Link{
+		CommonAttributes: newCommonAttributes(),
+		Href:             href,
+	}
 }
 
 // Check checks the Link for incompatibilities with RFC4287. It returns an