MAINT: split distributions.py into three files
MAINT: remove globals() as suggested by @evr-br
BUG: make curve_fit() work with array_like input.  Closes gh-3037.
MAINT: take argsreduce and rv_generic back out of the stats namespace
MAINT: move rv_discrete and rv_continuous into the distribution infrastructure module and prune redundant imports
MAINT: remove more redundant imports from the distribution infrastructure module
MAINT: remove unnecessary functions make_dict and reverse_dict
Merge pull request #3134 from argriffing/retry-split-distributions

MAINT: split distributions.py into three files
Merge pull request #3166 from rgommers/curvefit-list-input

BUG: make curve_fit() work with array_like input.  Closes gh-3037.