[css3-ui] syntax of property value definitions (Issue 34 & 41)

As raised in:
https://wiki.csswg.org/spec/css3-ui?&#issue-new34
https://wiki.csswg.org/spec/css3-ui?&#issue-new41

the text-overflow property defines it’s value as:

( clip | ellipsis | <string> ){1,2} | inherit 

also, all other properties in defined in the css3-ui specification list ‘inherit’ as a possible value

However:

1) as defined in http://dev.w3.org/csswg/css-values/#component-combinators, we should use [] for grouping, not ()

2) as defined in http://dev.w3.org/csswg/css-values/#component-types we should not specify css-wide values like inherit in every property

The patch attached to this mail fixes both of these issues for all properties in css3-ui (except for icon and nav-index, which we have decided to drop, to avoid dependencies between edits)

 - Florian