prevent collision if i18n function already exists

bibtexbrowser.php

@@ -353,6 +353,7 @@ function _zetDB($bibtex_filenames) {
 } // end function setDB
 
 // internationalization
+if (!function_exists('__')){
   function __($msg) {
     global $BIBTEXBROWSER_LANG;
     if (isset($BIBTEXBROWSER_LANG[$msg])) {
@@ -360,6 +361,7 @@ function __($msg) {
     }
     return $msg;
   }
+}
 
 // factories
 // may be overridden in bibtexbrowser.local.php