Focusing on “an old and subtle issue in contract law” — the “notoriously murky” distinction between “liquidated damages and limited remedies, on one hand, and alternative modes of performance on the other” — Judge David F. Hamilton specially concurred in the 7th U.S. Circuit Court of Appeals’ decision to affirm a judgment that tossed Brian Hughes’ breach of contract class action against Southwest Airlines.Hughes alleged he was scheduled to fly on one of hundreds …