TST: stats: add another test for find_repeats()
MAINT: stats: simplify (and speed up a bit) some code in wilcoxon()
BUG: sparse: The dtype argument to the dok_matrix constructor was not handled correctly when the input data was a list of lists.
Changed base.__pow__() to use O(lg N) binary power algorithm.
Fixed bug in new spmatrix.__pow__
Added a test for __iter__(). Need to decorate for types that don't support that method.
Overrode test_iterator() for DIA and COO since they don't have __getitem__
and added @dec.knownfailureif for BSR
Merge pull request #506 from WarrenWeckesser/tweak-wilcoxon

MAINT: stats: A small improvement to the wilcoxon code
Merge pull request #513 from Daniel-B-Smith/master

ENH: sparse: small performance improvement in __pow__

Use O(log N) rather than O(N) algorithm
BUG: sparse: coo_matrix.todia() would fail when the matrix was all zeros.
Merge pull request #511 from WarrenWeckesser/dok-ctor-bug

BUG: sparse: The dtype argument to the dok_matrix constructor was not handled correctly