Backports for 1.3.1

What does the merge request do?

• Backports for small, self-contained fixes for 1.3.x (!580 (merged), !586 (merged),!598 (merged), !599 (merged), !600 (merged), !603 (merged))
• updating the XAML submodule
• bumping the version number to 1.3.1

The Windows pipeline is currently broken but tests work locally for me on Windows.

Checklist

• Add unit tests (if applicable)
• Changes to inkex/ are well documented
• Clean merge request history