Kumaraswamy distribution
Raised cosine distribution
U-quadratic distribution
Von Mises distribution
Test args for new distributions
Erlang distribution
Non-central chi distribution
F distribution
Fisher's z-distribution
Fréchet distribution
Inverse-gamma distribution
Fix some doctest failures
Tests for new distributions
Add new distributions to the doc
Fix tests for new random distributions
Added Chi-squared distribution
Fix errors and typos in the docstring of chi-squared
Merge pull request #1413 from raoulb/more_distributions

WIP: More distributions