Chi square test for variance

[Anders]

Kolmogorov-Smirnov test and Student test are also important and are used a lot so as parisse suggested it would be a great addition to include the whole patrisse's list of test:
- chisquaret (chi2 test)
- normalt (normal)
- studentt (Student)
- kolmogorovt (K.-Smirnov)
- wilcoxont (Wilcoxon)