Fix `freqdec`'s URL and add `rangeslider.js`

Close #306.
add `position: sticky` entry

Fixes #276
Merge pull request #307 from cvrebert/master

add `position: sticky` entry
regenerate index.html to pull in updates
Remove trailing whitespaces from posts

Close h5bp/html5please#309.
Merge pull request #310 from cvrebert/regenerate-index-html

Regenerate `index.html` to pull in updates
Rename `readme.md` to `README.md`
Recommend Spectrum as `input type=color` polyfill

Reasons include:

* it's actively maintained
* it was good enough to get added to WebKit/Blink's dev tools
  http://bgrins.github.io/spectrum/#why-devtools
* it's MIT-licensed
* it's widely compatible (IE 6+)
* it has CI and a test suite set up
* it has an issue tracker (one of its competitors doesn't)

Close h5bp/html5please#311.
Update input-datetime.md

the link to webshims was pointing at their old github repo. Changed it to : http://tests-anciens.ljouhet.net/webshims/
update node.js commands in README

Fixes #308.
Merge pull request #313 from cvrebert/patch-1

Update dev commands in README
Update input-color.md

I don't know whether the status should still be 'avoid', since Firefox now supports this too....
Update input-color.md

Grouped Chrome and Opera together, since they both use Blink. Renamed Webkit to Safari.
Merge pull request #314 from zygous/patch-1

Update input-color.md
remove <ruby> "basic fallback" link (returns 404)
Merge pull request #315 from wilddeer/patch-1

remove <ruby> "basic fallback" (link returns 404)
add Stickyfill as another css-sticky polyfill
add css-sticky polyfill descriptions
add "[spec] can be subject to change"
Merge pull request #316 from wilddeer/patch-2

add Stickyfill as another css-sticky polyfill