In ut_output_table_buffer, when get_lines is called there should be a timeout thrown if no lines can be obtained after x seconds.

This is because if we request get_lines and don't run a corresponding TestRunner (as happening in utPLSQL/utPLSQL-cli#20), we only have the very big timeout of 4 hours in the reporters.
We should at least check that something is happening and act appropriately if not.