Revert version checking code

Checking version with `hlexists()` does not work as expected.
Add notes about problems on `vertical-align` etc

This closes #1.
Remove History section
Follow WD-css-lists-3-20140320

See also: http://www.w3.org/TR/2014/WD-css-lists-3-20140320/
Follow WD-css-flexbox-1-20140325

See also: http://www.w3.org/TR/2014/WD-css-flexbox-1-20140325/

This change is for spec name change.
Add css-line-grid-1.vim and test

See also: http://www.w3.org/TR/2014/WD-css-line-grid-1-20140403/
Add css-scoping-1.vim
Fix `@supports` highlighting in HTML files