Renamed / clarified documentation for ends_of_turn to ends_of_one_state
to match with planned new specification for simulating whole turns.
Specified and implemented depth-first and turn-first simulations in the
base Game. Now simulation of specific game types should be easy and leave
customization to focus only on what is unique to each game type.
Changed implementation without changing specification of capture. Uses
new depth-first simulation method in base Game.
change depth-first simulation to just "all_ends_of_turn"

Because... it turns out that simulation of randomized ends of turn
is much more effective on average than the depth-first way. Maybe
due to early detection of duplicate boards?
Added specification to base Game for overall effects on actors during
simulation. No new implementation or bugfixes necessary.