Add debug mode that lowers sandbox restrictions

Now you can print and do other things in your AI, if you run the game with a
--debug option. The tournament is run without it. The purpose of this option is
to make testing easier.
Remove an empty loop
Properly determine tournament's winner

Code would pick the species with highest score, even an extinct one. Fixed to
consider only living creatures.

Still can be improved to handle a case when all remaining species die in one
turn.