on_delete, on_select callbacks for app / some localization / some handling with data objects

1. on_delete and on_select callbacks for app through form_data structure (for as example a simple image viewer).

2. Localization for the camera function.

3. Some handling of data object to get them (instead of a string) back after submit.
```
{
  title: t("Type"),
  key: :type,
  items: [["T1", obj_t1],["T2", obj_t2]],
  type: :picker
}
```
For singe value object set the "form_obj:" in the form_data.