add chain branching strategy
add chain to imports
factor debug to onaction and write
onaction imports
add sfilter strategy
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