Indicate external links

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

@@ -23,6 +23,7 @@ public class NavMenuItem {
     private int icon;
     private int title;
     private Integer count = null;
+    private boolean external = false;
     private boolean warning = false;
     private boolean separated = false;
     private Runnable click;
@@ -47,6 +48,11 @@ public class NavMenuItem {
         this.count = count;
     }
 
+    NavMenuItem setExternal(boolean external) {
+        this.external = external;
+        return this;
+    }
+
     void setWarning(boolean warning) {
         this.warning = warning;
     }
@@ -72,6 +78,10 @@ public class NavMenuItem {
         return this.separated;
     }
 
+    boolean isExternal() {
+        return this.external;
+    }
+
     boolean hasWarning() {
         return this.warning;
     }