corrected k_means in docstring
rearranged imports from general to specific
moved and renamed _make_nonnegative() and _safe_min()
added option to use mini-batch k-means
use dia_matrix
renamed 'preprocess' to 'normalize'
use sklearn.utils.extmath.norm
base class __init__ is no longer abstract
added more information to error messages
also use norm in _project_and_cluster()
make test more sparse
made 'bicluster' a submodule of 'cluster'
updated docs to reflect move
removed svd_kwargs argument
added n_svd_vecs parameter
tests use ParameterGrid to avoid deep nesting
removed kmeans_kwargs
added some useful k-means parameters
updaed documentation