print stats

[lacava]

create and print stats based on verbosity.

if verbosity = 0, nothing should be printed.
if verbosity = 1, the current best score, current generation, and a portion of the current archive should be printed. at the end, the archive should be shown.
if verbosity = 2, the population equations each generation, the current part of execution, the parameter settings should be printed, in addition to what is printed with verbosity =1.

[lacava]

see f48686d