dstats alpha 4

[dsimcha]

The latest alpha of my statistics library is out on Scrapple.  I've decided
that it needed a catchier name, so I've renamed it to dstats.  Anyhow, it's
undergone some pretty drastic upgrades since the last time I announced a
release.  We now have the following relatively major stuff that wasn't there
before, plus some minor stuff that I forgot to mention.

Much improved docs.

Much better API organization.

A decent information theory module, with entropy, mutual information, joint
entropy and conditional mutual information.

Mean, variance, standard deviation, skewness, kurtosis, Pearson correlation
and covariance can now be calculated online as data is received, or from arrays.

Improved memory allocation for scratch space used within functions by using
the TempAlloc region allocator.

A combination generator that can generate all (N choose R) combinations from a
sequence.

Equal frequency and equal width binning functions.

Laplace and Cauchy CDFs and inverse CDFs

Student's one- and two-sample and Welch's T-tests.

The Waltz-Wolfowitz test for randomness of a sequence.

Random number generation from the normal, Cauchy, Laplace, Bernoulli,
binomial, and hypergeometric distributions.

Lots of bug fixes and performance improvements.

Unfortunately, D1 doesn't have enough features for me to create the API I want
in dstats, so I've been targeting the bleeding edge compilers.  dstats will
only work on DMD 2.022.  Even with 2.021, the TLS GC bug that was fixed in
2.022 will break it.