Expand distributions

[richfitz]

We're starting to get a reasonable library of distributions, but there are some other ones not implemented yet that I am aware people do use with odin

• hypergeometric
• multivariate hypergeometric (used by squire)
• negative binomial (we have density for this)
• gamma

Other ones supported in base R that might be useful

• beta
• cauchy
• chi-squared
• geometric
• lognormal

For continuous distributions we could always implement some general support for inversion then replace with better algorithms as needed. Better to do after implementing #308 properly

https://beamdocs.fnal.gov/AD/DocDB/0028/002887/002/sampmet.pdf for hypergeometric