1) Create public javascript() and css() functions and turn __call()
into a private function to protect us against having some random
type show up in there. Otherwise anything you put in the 2nd
argument gets emitted in the header which is a security hole.
2) Fix a bug ("$key = $key[0]") which was breaking functionality.
Eliminate the hex check, it's not really necessary in the majority
case and doesn't hurt us in edge cases.
3) Convert some empty() calls to !, no need for a function call there.
4) Add phpDoc.
1) CSS files are added to the combined version by use of $theme->css() or $theme->css_theme() methods
2) url references in the css are converted to full paths as opposed to relative
3) @import statements in the css are resolved as well.
4) need to move the [if IE] statements into the css files so the will be honored in the browser. currently the ie fix css are always included.
