TST add test for minibatch k-means reassigns.
FIX bug where random state was reset in each call to partial_fit, such that reassignment either occured never or always.
FIX bug where distances were of illegal shape
FIX crash when to_reassign.sum() > X.shape[0]
TST split test for partial_fit and fit
TST add additional test for batch_size > n_samples in fit.
MISC rename random.pyx to _random.pyx
ENH backport np.random.choice.
FIX broken tests for minibatch k-means
FIX use choice in minibatch_kmeans
FIX another (two?) bugs: the default code path didn't ever compute distances.
skip doctests
simplify tests
remove redundant code
FIX up the rest of the stuff. Introduce .5 as a magic number. Hurray for magic numbers?
DOC more / better documentation
FIX reset counts of reassigned clusters.
ENH never reassign everything, more meaningful tests.
TEST: fix test failing due to numeric instability
COSMIT: address misc comments