Southwest Airlines and Delta Air Lines are scheduled to be back in court Monday in their ongoing legal dispute over gates at Dallas Love Field. Love Field, owned by the city of Dallas, is constrained to 20 gates. Dallas-based Southwest Airlines (NYSE: LUV) controls 18 of the 20 gates. The dispute centers around Gate 15, which Southwest and Atlanta-based Delta (NYSE: DAL) have been sharing for more than a year. Southwest paid $120 million to lease two gates, including Gate 15, from United Airlines…