Added a ToStringRole to summarize the model items (for tool tip and QR code).

model/modelitem.cpp

@@ -44,6 +44,20 @@ bool ModelItem::setItemData(const QMap<int, QVariant>& changedValues) {
   return valueChanged;
 }
 
+QString ModelItem::toString() const {
+  QString result;
+
+  QListIterator<UserRoles> i(USER_FACING_ROLES);
+  while (i.hasNext()) {
+    const UserRoles role   = i.next();
+    const QString roleName = ROLE_NAMES.value(role);
+    const QVariant value   = data(role);
+    // result.append(value.toString());
+    result.append(QString("%1: %2\n").arg(roleName, data(role).toString()));
+  }
+  return result;
+}
+
 QJsonObject ModelItem::toJsonObject() const {
   QJsonObject itemObject;
   // TODO add UUID and dates (entry, modification, end)