fix upstream markdown ambiguities, inconsistencies, and ordered listing antipatterns

[naturallymitchell]

needs: 1) feature complete structured writing, automatic list item numbering 2) unambiguous syntax 3) round-tripping between markup and markdown

numbering # for list ordering
portioning % for text sectioning, paragraphs
bulletting * for unordered listing

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raw notes:
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bug: ordered list syntax uses ambiguous, cumbersome, hardcoded symbols

https://spec.commonmark.org/0.28/#ordered-list-marker
https://en.wikipedia.org/wiki/Hard_coding (antipattern)

using unique, hardcoded characters for each list item, and then an ambiguous ending character is breaking my content. I'd like to change this syntax to a single character syntax.

the number sign, #, would make the most sense to me, since we're numbering things. this would make for an easy fix with nesting ordered lists, because then we could use multiple markers for list depth.

related: # [ ]

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bug: heading syntax uses a number symbol, instead of a portion symbol

https://spec.commonmark.org/0.28/#atx-heading
https://en.wikipedia.org/wiki/Number_sign

this bug also breaks numbering things. see []#

percentage is a portion calculated in terms of the rest of the portions, but it's the closest general character I can find to indicate a portion

the only other one I can think of is + a plus sign, but that's part of the problem I'm trying to solve. I would like to better organize content across documents for a combinatorial value whose mechanisms work differently than simple addition.

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• Nested ordered lists indented with 2 spaces are broken - Spec - CommonMark Discussion
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• Indentation requirement of sub lists inside ordered list items - Spec - CommonMark Discussion
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