Changes defs to lambdas

This does not improve anything, but for a passionate JavaScript programmer
this feels better ;-)
Fixes at least the comment on selection randomness
Adjusts parameters

And adds brute force implementation (commented out chunk at the end)
And uses 2 to indicate head of the snake
Changes log to keep only one individual per fitness.

Creating a complete log wastes too much time.
rubyfies the code
Changes board to more readable style

And fixes flood_fill after this was broken by changing it to lambda