Formatting

slide-ng format [slides.md]

Rewrites the file with the same parser that reads it. Slide by slide it:

• trims blank lines around the content, leaving one blank line after the frontmatter and before the next ---
• prints the frontmatter again as clean YAML, keeping comments
• puts the speaker note in an HTML comment at the end

Files that src: imports are not touched. Name them as arguments to format them too. A file that is already tidy is reported as such. The VS Code extension can run it from the editor (first version, not released). There is no Prettier plugin.