change fit_mle to fit for Cauchy (the current implementation is not MLE)
Enhanced estimation interface for Categorical
More functions for estimating Categorical
Enhanced interface for Binomial estimation
add @inbounds for Gamma estimation
minor rearrangement of Dirichlet estimation code
@inbounds for Dirichlet estimation
add Estimator type and interface

This is a nonintrusive modification. By delegating estimate(e::MLEstimator, x) to fit_mle, we no longer need to make any change to original codes.
include estimators.jl
Added Normal-inverse-{gamma/Wishart}.
posterior_sample returns a Distribution with params sampled from posterior.
Added posterior_sample specialization for univariate Normal.
Added MvNormalSuffStats to store sufficient statistics for MVN.
Posterior computations for Normal-inverse-Wishart.
Handle Gamma prior on precision in conjugates.jl.
Placeholders for normalgamma.jl, normalnonconj.jl, and normalwishart.jl.
NormalInverseGamma uses variance param.
Implemented basic NormalGamma.
Moved multidimensional log-gamma function to specialfuns.jl.
Renamed matrix parameter to match Murphy and fixed logpdf.