Update index.html.

* add `meta charset`
* specify lang
* remove default type for css
Update uglify to v2.4.13.
README.md: add link to the website.
Make `textarea` resize only vertically.
master.css: Minor tweaks.
Add missing semicolon.
Switch to the minified underscore build.
Fix a few variable redefinitions.
sss
Slightly improve markup.
Ignore _site.