more robust testing for randint and randfloat

[make-github-pseudonymous-again]

chi square test

reference:

• http://math.stackexchange.com/questions/2435/is-there-a-simple-test-for-uniform-distributions
• http://en.wikipedia.org/wiki/Pearson's_chi-squared_test

[make-github-pseudonymous-again]

could extend to shuffle and sample procedures