Adding a word separator to fURL::makeFriendly

I think this would be a great addition, I've taken the easy way out and done the following a few times:

str_replace('_', '-', fURL::makeFriendly($uglyUrl));

I think it would be a great addition, one I would personally use, here is a patch

@@ -92,21 +92,22 @@
 	 * 
 	 * @param  string   $string      The string to convert
 	 * @param  interger $max_length  The maximum length of the friendly URL
+	 * @param  string   $separator   Character to use between words in URL, defaults to '_'
 	 * @return string  The URL-friendly version of the string
 	 */
-	static public function makeFriendly($string, $max_length=NULL)
+	static public function makeFriendly($string, $max_length=NULL, $separator='_')
 	{
+	    $regexSeparator = preg_quote($separator);
 		$string = fHTML::decode(fUTF8::ascii($string));
 		$string = strtolower(trim($string));
 		$string = str_replace("'", '', $string);
-		$string = preg_replace('#[^a-z0-9\\-]+#', '_', $string);
-		$string = preg_replace('#_{2,}#', '_', $string);
-		$string = preg_replace('#_-_#', '-', $string);
-		$string = preg_replace('#(^_+|_+$)#D', '', $string);
+		$string = preg_replace('#[^a-z0-9\\-]+#', $separator, $string);
+		$string = preg_replace('#' . $regexSeparator . '{2,}#', $separator, $string);
+		$string = preg_replace('#(^' . $regexSeparator . '+|' . $regexSeparator . '+$)#D', '', $string);
 		
 		$length = strlen($string);
 		if ($max_length && $length > $max_length) {
-			$last_pos = strrpos($string, '_', ($length - $max_length - 1) * -1);
+			$last_pos = strrpos($string, $separator, ($length - $max_length - (strlen($separator)) * -1);
 			if ($last_pos < ceil($max_length / 2)) {
 				$last_pos = $max_length;
 			}