Cards, custom fields are displayed in alphabetic order

This should fix #3367

models/cards.js

@@ -689,7 +689,7 @@ Cards.helpers({
 
     // match right definition to each field
     if (!this.customFields) return [];
-    return this.customFields.map(customField => {
+    const ret = this.customFields.map(customField => {
       const definition = definitions.find(definition => {
         return definition._id === customField._id;
       });
@@ -715,6 +715,10 @@ Cards.helpers({
         definition,
       };
     });
+    if (ret.definition !== undefined) {
+      ret.sort((a, b) => a.definition.name.localeCompare(b.definition.name));
+    }
+    return ret;
   },
 
   colorClass() {