fix: markdown headings, dash lists and table separators

[lvolland]

hey! found this highlighting a readme with md.

the cmnt rule (=|-)\1+ isn't anchored, so it fires on any -- or == in a line. your own readme hits it: every |------| in the language table is painted as a setext underline. -/+ bullets, 1) lists and atx headings had no rule.

| name | class |
| ---- | ----- |
# heading
- dash bullet
+ plus
1) paren
foo -- bar

today only the ---- cells and the -- are colored, as cmnt. expected: table row plain, # as section, the three bullets as kwd.

fix: anchor cmnt to a whole line (^[ \t]*(=|-)\1+[ \t]*$), widen the list rule to [*+-] / \d+[.)], add a section rule. the list rule ends with ([ \t]|$) so a marker alone on its line stays lit while you type — same spirit as the optional closing delimiters elsewhere. +81 bytes, ~+69 minified (estimated). test.md updated; it's the only fixture that moves.

notes

• any --/== not alone on its line loses its cmnt: i--, a == b, --verbose, tables with or without outer pipes.
• token edges move: spaces around a setext underline now sit inside the span. same rendering, different snapshot.
• # heading and a bare # stay uncolored, to keep 4-space code blocks dark.
• section isn't styled in github-dim.css or termcolor.js — pre-existing, but md makes it visible.
• happy to move section lower if you prefer the ini/toml ordering 🙂