Imroved list rendering and definition list support

[kyerpotts]

I have some visual enhancements to list rendering that I've been rebasing onto development with every so often, I was wondering if there's any interest in including them in Crossink permanently.

The full list of improvements are:

List Rendering

• Numeric markers for ordered lists
• Independent numbering and indentation for nested lists
• Indent aligned text for wrapped item text blocks

Definition Lists

• <dl>, <dt> and <dd> tags are treated as block elements
• Footnote preview block detection for definition list elements

Full footprint is +1.5KB on Firmware Flash and +48bytes for Parser
I haven't made any real attempt at optimising the memory usage for the changes, I'm happy to do so if these changes look good.

[kyerpotts]

@uxjulia I know you're quite busy and this will probably come off as demanding, but are you able to confirm whether or not you want me to create a pull request with this work?

[uxjulia]

This would be an easy yes if the ESP32-C3 devices were no longer supported. As it stands though, those devices already struggle with a lot of the CSS parsing. I'm honestly afraid to add more. And this isn't a highly requested feature so I'd rather leave well enough alone for now. This might be something I'll revisit when x3/x4 support becomes LTS

[kyerpotts]

No worries that's a fair call. Appreciate the response 😄