complete rearrangement an splitting into functions

src/index.php

@@ -77,7 +77,7 @@ function source($dir, $file, $mime=NULL) {
 }
 
 /** Output only a part of a file */
-function range($path, $size, $mime) {
+function fileRange($path, $size, $mime) {
   $ranges = array_map('intval', // Parse the parts into integer
                       explode('-', // The range separator
                               // Skip the `bytes=` part of the header
@@ -121,7 +121,7 @@ function output($path) {
   @ini_set('zlib.output_compression', 'Off');
   header('Content-type: ' . $mime);
   if (isset($_SERVER['HTTP_RANGE'])) {
-    range($path, $size, $mime);
+    fileRange($path, $size, $mime);
   } else {
     header('Content-Length: ' . $size);
     @readfile($file);