BUG: integrate: odeint crashed when the integration time was 0.

When only a single time point (or only a single repeated time value)
was given along with the argument full_output=True, a KeyError was
raised because the _msgs dict didn't have the key 1 (the 'istate'
value returned by the Fortran solver when no work was done).

Closes gh-4282.
TST: add unit test for stats.kstat, was not yet covered.

`kstat` still needs full review, see Statistics Review issue gh-675.
MAINT: add .idea/* (PyCharm config files) to .gitignore
MAINT: style cleanups in stats/stats.py and stats/morestats.py
TST: fix last signification digit in expected results for stat.kstat test.

Addresses review comment from Warren on PR 3680.

[ci skip]
MAINT: != -> not_equal in hamming distance implementation
TST: spatial: regression test for gh-4290
Merge pull request #3 from larsmans/hamming-unequal-length

TST: spatial: regression test for gh-4290
Merge pull request #3680 from rgommers/stats-cleanup

Some cleanups in stats
DEP: deprecate stats.pdf_fromgamma.  Closes gh-699.
Merge pull request #4293 from argriffing/improve-hamming-error-message

MAINT: != -> not_equal in hamming distance implementation
Merge pull request #4284 from WarrenWeckesser/bug-odeint-single-time

BUG: integrate: odeint crashed when the integration time was 0.
Merge pull request #4287 from rgommers/deprecate-pdffromgamma

DEP: deprecate stats.pdf_fromgamma.  Closes gh-699.