Issue/leafo/644v2

[Cerdic]

This is now really fixin #644 as I checked the whole compilation of BS4 and fixed each bug in the output css.

The compilation with scssphp now only differs from the dist css file on the following points:

• quote on some fonts name BlinkMacSystemFont, Segoe UI, Roboto vs BlinkMacSystemFont, "Segoe UI", Roboto
• precision on float value .3333333333
• leading zero values 0.5rem vs .5rem
• some combinations of selectors not in the same order (eg input-group >...)
• some slight differences on the color computation like #ffe7a0 vs #ffe8a1
• spaces, newlines and indentation

and also of course the prefixed properties, selectors and values that are in the dist bootstrap.css

I think we can say it's an acceptable result :)