add list around theano_function outputs
raise NotImplementedError if theano.stacklists dne

At the time of this commit this feature in Theano is not yet released
and so depends on the development version.
subs(...).evalf -> evalf(subs=...)
New import diagnostics: list problems, list imports

Keep this test on @XFAIL for now, the errors that it finds will go in a separate commit.
Usage text correction.
Merge pull request #2578 from toolforger/diagnose-imports

New import diagnostics: list problems, list imports
Merge pull request #2614 from mrocklin/computation-docs-2

Computation docs 2
unit test for latex bug
bugfix in latex printing of unevaluated Mul objects
a similar test to check that latex() respects evaluate=False in Pow objects
Fix evalf for zero sum (issue 3273)
faster ``_choose_factor``
Merge pull request #2620 from pernici/mp4

faster ``_choose_factor``
Merge pull request #2617 from hacman/latex_fix

Latex fix
Merge pull request #2618 from skirpichev/3273-evalf-0sum

Fix evalf for zero sum (issue 3273)