static public function php($dir,$args=[]) Very quickly deliver a php file by appending the url to a directory
Request url must end with a forward slash /
GET params are removed from url .. is removed from url
static public function file($dir, $url=null) Very quickly deliver a file. Supports browser caching.
Uses a very fast implementation for getting mimetypes. Each file extension has a *.txt file that contains its mimetype.
static public function send_file($file_path) send headers & output file