Use "state" only for game trees
Make a new world while listing moves to play cards
Add makeGameTreeAfterPlaying
Do not use 'play' step in tests on Fill the Earth
Do not use 'play' step in tests on Multiply
Do not use 'play' step in tests on Planning Sheep
Do not use 'play' step in tests on Sheep Dog
Remove obsolete setUpWorld
Remove obsolete 'play' step
Remove obsolete makeWorld
Merge branch 'refine-state'