* src/mainwindow.{cc,h} (MainWindow::autorun_idle): New method
which first invokes the file search and the regex search after
that, unless the user hit the Stop button in between.
(MainWindow::initialize): Connect Glib::signal_idle() to the new
autorun_idle() method instead of controller_.find_files.slot().
(MainWindow::busy_action_leave): Don't reset busy_action_cancel_
so that autorun_idle() can test this flag to determine whether
the busy action was cancelled by the user.