Adding a deleteLink helper
Adding insert for entity object and insertCallback.
+ [generateDeleteLink] method in entity, which generate a link for delete an object.
+ [__set] and [__get] method changed in Entity. It now return in the first case the value of the field.
  - if you want the referenced table instead of the field value in a template, use directly the table name.
  - if the field value and the table name are the seme, use the [table] method for have a direct acces on the table. (ex : user.table('team').name)