expr: test axis normalization on reductions
python: keepdims on reductions
expr: keepdims on std, var
pandas keepdims
common_subexpression uses dispatched subterms, not _subterms method
summary supports keepdims
python: summary keepdims compute
expr: summary __str__ includes keepdims
pandas summary keepdims
docs: summary str fix with keepdims
expr: split uses keepdims consistently on chunks
expr-split: aggregate_shape function
expr: _split -> _split_chunk, _split_agg
expr: split reasons about dimensions
expr: split reductions pass axis arguments through
remove unnecessary shape_div function
Merge branch 'master' into keepdims-python-pandas
split: doesn't compute agg if given
Merge pull request #762 from mrocklin/keepdims-python-pandas

ND-split