'Lineup.__init__' tests

Add tests for 'Lineup' constructor to confirm that 'order' is being
properly instantiated.
Fix 'Lineup.__init__'

Fix 'Lineup' constructor method.
'Player' delete cascade test

Add test to confirm that when a 'Player' is deleted, it is also removed
from every lineup in which it is contained.
'Player' delete cascade

Implement 'cascade' behavior for 'Player.delete' method. When a player
is deleted, it is first removed from every 'Lineup' that it was in.
Remove 'Lineup.to_dict_full'

Replace 'Lineup.to_dict_full' with 'Lineup.to_dict' everywhere. There
was really no need for that method, and it was making return values
unnecessarily complicated.
Merge branch 'player-cascade'