Improved detection and handling of document downloads (PDF, etc.)
The way DA presents some documents seems wonky and sloppily implemented.
-> DA might change (fix) their implementation and/or the script might stumble over some weird document representations.

Fixed an embarrassing number of typos in the comments (there will be some more, for sure).

Major rework of script:
- support multi-image deviations
- support deviations with original download enabled, but no original download button (free download is part of "..." ellipsis menu, instead).
- general improvements (fixed typos in comments, more robust coding, some refactoring)

author->artist for better clarity