'Change maximum line count'

@Slot()
def change_max_line_count(self):

    (mlc, valid) = QInputDialog.getInt(self, _('Buffer'), _('Maximum    line    count'), self.get_option('max_line_count'), 0, 1000000)
    if valid:
        self.shell.setMaximumBlockCount(mlc)
        self.set_option('max_line_count', mlc)
