Implements border width parsing

Per specs on http://www.w3.org/TR/CSS21/box.html#value-def-border-width
and http://www.w3.org/TR/CSS/
Renames MultiWidth to the more generic MultiSide
BorderWidth needs to include Common, not Color

No need for Color since there is no color parsing going on
Implements border-color parsing and refactors Color transforming

Refs: http://www.w3.org/TR/CSS21/box.html#propdef-border-color and
http://www.w3.org/TR/CSS/
Implements border_style parsing

Per specs on http://www.w3.org/TR/CSS21/box.html#propdef-border-style
http://www.w3.org/TR/CSS/
Implements border side parsing

Per specs at http://www.w3.org/TR/CSS21/box.html#propdef-border-top and
http://www.w3.org/TR/CSS/
Implements border parsing

This doesn't interpret "border" properties as "border-top",
"border-bottom", etc. This parses them directly to the bottom level of
"border-top-width", "border-top-style", etc.

That might come back to bite me, but going to give it a shot and see how
far it goes