prevent collision if i18n function already exists

bibtexbrowser.php

@@ -353,12 +353,14 @@ function _zetDB($bibtex_filenames) {
 } // end function setDB
 
 // internationalization
-function __($msg) {
+if (!function_exists('__')){
+  function __($msg) {
     global $BIBTEXBROWSER_LANG;
     if (isset($BIBTEXBROWSER_LANG[$msg])) {
       return $BIBTEXBROWSER_LANG[$msg];
     }
     return $msg;
+  }
 }
 
 // factories