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

icon.go

@@ -14,7 +14,10 @@ type Icon struct {
 
 // NewIcon creates a new Icon. It returns a *Icon.
 func NewIcon(uri string) *Icon {
-	return &Icon{URI: uri}
+	return &Icon{
+		CommonAttributes: newCommonAttributes(),
+		URI:              uri,
+	}
 }
 
 // Check checks the Icon for incompatibilities with RFC4287. It returns an