Allow displaying hidden namespaced elements

app/src/main/java/eu/faircode/email/HtmlHelper.java

@@ -387,7 +387,8 @@ public class HtmlHelper {
         for (Element e : parsed.select("*")) {
             String tag = e.tagName();
             if (tag.contains(":")) {
-                if (ns == null || tag.startsWith(ns)) {
+                if (display_hidden ||
+                        ns == null || tag.startsWith(ns)) {
                     e.tagName(tag.split(":")[1]);
                     Log.i("Updated tag=" + tag + " to=" + e.tagName());
                 } else {

app/src/main/res/layout/fragment_options_privacy.xml

@@ -236,6 +236,7 @@
             android:layout_marginEnd="48dp"
             android:text="@string/title_advanced_display_hidden_hint"
             android:textAppearance="@style/TextAppearance.AppCompat.Small"
+            android:textColor="?attr/colorWarning"
             android:textStyle="italic"
             app:layout_constraintEnd_toEndOf="parent"
             app:layout_constraintStart_toStartOf="parent"