tweak format again

Dependencies

• [2] TSV3KPBR tweak format of test failures
• [3] ORRSP7FV deduce test names on failures
• [*] 3QNOKBFM beginnings of a test harness

Change contents

• replacement in app.lua at line 454
  [2.222]→[2.222:313](∅→∅)
  − local full_error = test_name..' -- '..file_and_line_number..' '..err_without_line_number
  [2.222]

  [3.61148]
  + local full_error = test_name..' -- '..err_without_line_number..' ('..file_and_line_number..')'