TorrentCreator: add .torrent extension only when missing

src/createtorrent_imp.cpp

@@ -191,6 +191,7 @@ void createtorrent::on_createButton_clicked(){
   QString destination = QFileDialog::getSaveFileName(this, tr("Select destination torrent file"), last_path, tr("Torrent Files")+QString::fromUtf8(" (*.torrent)"));
   if(!destination.isEmpty()) {
     settings.setValue("CreateTorrent/last_save_path", misc::removeLastPathPart(destination));
+    if(!destination.toUpper().endsWith(".TORRENT"))
       destination += QString::fromUtf8(".torrent");
   } else {
     return;