v0.9.4

A block-level <!-- ... --> fell through to the paragraph case and rendered as escaped visible text, publishing authoring notes intended only for source readers. Single-line and multi-line comments are now consumed and emitted as nothing.

Per CommonMark an unterminated comment runs to end of document; asserted by a test so the behaviour is deliberate. Inline comments are still passed through.

32/32. Sabotage-tested with two controls that stay green, so a stripper that deleted too much would be caught.