Add support for custom HTML and XML content-type

render/html.go

@@ -58,7 +58,7 @@ func (r HTMLDebug) loadTemplate() *template.Template {
 }
 
 func (r HTML) Render(w http.ResponseWriter) error {
-	w.Header()["Content-Type"] = htmlContentType
+	writeContentType(w, htmlContentType)
 	if len(r.Name) == 0 {
 		return r.Template.Execute(w, r.Data)
 	} else {

render/xml.go

@@ -16,6 +16,6 @@ type XML struct {
 var xmlContentType = []string{"application/xml; charset=utf-8"}
 
 func (r XML) Render(w http.ResponseWriter) error {
-	w.Header()["Content-Type"] = xmlContentType
+	writeContentType(w, xmlContentType)
 	return xml.NewEncoder(w).Encode(r.Data)
 }