markdown-fill-paragraph could perhaps benefit from rearchitecting

[glyph]

There are a bunch of issues affecting paragraph-filling, so it might be good to consider a new approach rather than fixing these whack-a-mole. I am linking them all here so that if anyone were to pick up such an issue they will get visibility into the others:

• markdown-mode-fill-paragraph mangles inline attributes by treating them as text #862
• Comments do not fill properly #833
• Inline styles fail to syntax-highlight when broken by newlines #568
• Indented tables get wrapped by fill functions #315
• lines beginning with pipe | in math mode are not wrapped with fill-paragraph #314
• fill-paragraph is a no-op in YAML frontmatter #297

(Please feel free to close if this is not a helpful organization tool.)