Pyrule-compendium

* Fix `get_image().download()` image corruption.
* Fix incorrect types on `defaults.defaults.with_url`.

Create entry image object.

* Add default image names for `download_entry_image`.
If no `output_file` is given, it defaults to the entry's name with a `.png` extension.
* Move exceptions and utils to seperate files.

More hardcoded types.

Clarify code comments on default parameters.

Add configurable timeout for compendium class applying to all API calls, defaulting to `None` (no timeout).