Add full suite of probability distributions

[heydenberk]

Currently supported:

• [x] Normal(µ, σ²)
• [x] Uniform(n)
• [x] Uniform(a, b)

To add:

• [x] Log-normal(µ, σ)
• [ ] Bernoulli(p)
• [ ] Binomial(n, p)
• [ ] Geometric(p)
• [ ] NegativeBinomial(p, r)
• [ ] Hypergeometric(N, M, n)
• [ ] Poisson(λ, t)
• [x] Exponential(λ)
• [ ] Gamma(λ, r)
• [ ] Beta(α, β)
• [ ] ChiSquared(ν)
• [ ] Student's t(ν)
• [ ] Hotelling's T-squared
• [ ] F(ν1, ν2)

Prior art:

• PyMC3
  • Continuous distributions
  • Discrete distributions
  • Multivariate distributions
• Python standard library
  • Standard library random module
• numpy
  • np.random