WKHTMLtoPDF provides limited control for external fetching
so that will now be disabled by default unless
ALLOW_UNTRUSTED_SERVER_FETCHING=true is specifically set.
This new option will also control DOMPDF fetching.
- Removed ZIP system for now, until the idea can be fleshed out.
- Added testing to cover.
- Upgraded used library.
- Added custom handling for BookStack callouts.
- Added HTML cleanup to better produce output for things like code
blocks.
