Box leagues/ladder

• Add ability to  run a box league 
• Look at https://boxleague.net
• == entity: tennisClub
•       Name, address, tel, notes, administrator, toilet, GPSlocation, parking, bar, changing rooms, showers 
• == entity:   boxLeague
•       tennisClub (relation), box league number (1, 2…. x), sets, promotion count, demotion count, date for completion 
• == players
•       Member of a specific box league at a specific club(s)
•  Box league then creates a list of fixture (grid), allows the users to enter their own score and.or the administrator. Includes walkover 
• Computer the winner/loser 
• Computes next season starting point.