Changed
- The `.copy_into()` method of `DAFile` now accepts `DAFile`,
`DAStaticFile`, `DAFileList`, and `DAFileCollection` objects as
the argument, as well as the direct file path of the other file.
Fixed
- Problem with converting to PDF after `update references` for some
tables of contents.
- The `.copy_into()` and `.from_url()` methods now update PDF and
image information after the file contents change.