Support Mozilla-specific pseudo-elements
Fix cases where one name is within another
add grammar and nodes for css3 media queries

grammar based off http://www.w3.org/TR/css3-mediaqueries/#syntax
Fixed support for media keywords
Merge from mozpseudo
Merge from branch media
Support @supports
Support negative numbers in calc expressions
Add context to error messages
Generalize rule_set.media to rule_set.parent_rule, matching DOM Level 2 Style
Make parent_rule null instead of empty array
Add line number to error messages
Merge pull request #2 from JasonBarnabe/linenumbers

Add line number to error messages
issue 3 Retrieve original code of nodes
issue 8 Allow functions with no parameters
#11 Support CSS variables
#12 @supports with URL marked as invalid
#10 Nested parentheses in calc
Version 4.0.1
#13 Support vh unit