Added
- The `.user_access()` and `.privilege_access()` methods of `DAFile`.
- The `persistent`, `private`, `allow users`, and `allow privileges`
specifiers for `attachments` and field modifiers for `datatype:
file` fields.
Fixed
- User could not access a private and persistent file after the
deletion of the session in which the file was created.
- Issue with `js show if` and `list collect`.