Added highlight group for commas in attributes
Adding support for css hacks

This commit may be somewhat controversial. It essentially styles known
css hacks like (* and _) as if they were vendor prefixes (linked to the
Comment group).
More descriptive comments for cssHacks group
Fix inline/inline-block/inline-box

There was an issue where inline-block would not be detected properly due
to clashes with the keyword inline. This commit fixes that.

Also, there is no such thing as inline-table (at least that I
could find).

Also, inline-box is version of inline-block that Mozilla used in earlier
versions of Firefox.
Merge pull request #16 from amadeus/css-hacks

Adding support for css hacks
Merge pull request #20 from amadeus/inline-block-fix

Fix inline/inline-block/inline-box
Merge pull request #19 from amadeus/add-attr-comma

Added highlight group for commas in attributes