Fixes MarshalXML() and renames initial "H" tag to "map".

gin.go

@@ -83,6 +83,7 @@ var (
 
 // Allows type H to be used with xml.Marshal
 func (h H) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
+	start.Name = xml.Name{"", "map"}
 	if err := e.EncodeToken(start); err != nil {
 		return err
 	}
@@ -91,11 +92,11 @@ func (h H) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
 			xml.Name{"", key},
 			[]xml.Attr{},
 		}
-		if err = e.EncodeElement(value, elem); err != nil {
+		if err := e.EncodeElement(value, elem); err != nil {
 			return err
 		}
 	}
-	if err = e.EncodeToken(xml.EndElement{start.Name}); err != nil {
+	if err := e.EncodeToken(xml.EndElement{start.Name}); err != nil {
 		return err
 	}
 	return nil