reset Player.timeGoLiveFail to long.MinValue instead of long.MaxValue
note a bug involving moving non-live paths
rename CmdEvt to UnitCmdEvt, add new CmdEvt class that all commands inherit from
don't need to store LineBox GameObject separately
only display existing units in unit selection bar
use foreach to loop through unit types in make unit menu
move playerVisRemove(), exclusiveAdd(), exclusiveRemove(), calcExclusive() from Sim to Tile