Rewrite uris when inlining, with combine on.

In this mode, we read in the cache file. Since the path at which the cache
file's contents therefore changes, need to rewrite all uris inside that
cache file.

classes/casset.php

@@ -881,6 +881,8 @@ public static function render_css($group = false, $options = array(), $attr_dep
 				if ($inline)
 				{
 					$content = file_get_contents(DOCROOT.static::$cache_path.$filename);
+					// We'll need to fix the uris, unless they were rewritten absolutely to start with
+					$content = static::css_rewrite_uris($content, static::$cache_path.$filename, \Uri::string());
 					if ($options['gen_tags'])
 						$ret .= html_tag('style', $attr, PHP_EOL.$content.PHP_EOL).PHP_EOL;
 					else