Remove trailing spaces and use spaces consistently.
Normalize package.json.
Add .npmignore file.
Add JSHint support.

Use npm run check or npm run lint.
Fix a few JSHint warnings.
lib/markdown.js: more consistent style
Use double quotes in most places.
Update dependencies and follow semver.
test/interface.t.js: minor simplification.
Improve README.markdown.

Specify the language used to highlight and use code in more places.