Reuse result table in creature_look

Profiler indicated that creating new table each time creature look is called is
costly. This is because the table is filled from empty to N, causing a lot of
rehashing (allocated size is increased *2 every time). By reusing this table, it
will grow and then remain "big enough".

Profiler showed a massive improvement... but when the code runs without the
profiler, I see no gain.

I decided to deliver it because I do use the profiler, and it runs faster that
way.
Avoid the need to sort results of creature_look

Results of creature_look are built based on the content of a grid, which stores
creates in a hash set that does not prevent the order. This causes indeterminism
in tournaments. To avoid that, I've been sorting the results.

Profiler showed that it is faster to use order preserving arrays to implement
the grid than to sort those results, and I did that.
Require reaching turn limit to pass qualifications

Fixing a bug that declared species as successfully passing qualification even
when it didn't survive till the turn limit.

Now it works as was my original intention. If it goes extinct too soon, it
fails. This ways creatures are forced to eat (by a high turn limit) but cannot
eat everything (starvation risk).
Export math.min and math.max to sandbox

Now min and max are available in the sandbox. This fixes issue #3.
Make it possible to detect sandbox

It is useful to be able to add some debug prints etc. in your creature's code.
At the same time it is inconvenient to later remove that for submission.

This commit gives you a way to test for the active mode by accessing
World.SandboxDisabled, so now you can:

  if World.SandboxDisabled then
    print("looking for food")
  end
Update gitignore
Reduce energy based on amounts of computation

In order to kill creatures that may start executing an endless loop as well as
to encourage effective algorithms, I'm introducing a penalty for executing
instructions.

So far, running the brain had no cost, apart from the fixed turn cost and the
cost associated with made decisions. From now on, the longer it takes to execute
brain, the more energy it will cost.

I don't want to kill creativity or discourage complicated algorithms, so the
cost is very low. I'm not sure about the value, but I set it so that the longest
execution of a brain that I've seen in 1st edition will cost just 0.1 energy
points.