TST: remove incorrect (and useless) tests for rounding numbers.

Also some general cleanup in test_stats.py.  See gh-2482.
TST: fix equal comparison of float arrays in spatial.distance tests.

Closes gh-2482.
BUG+ENH: stats: Improve the 'fit' method of norm_gen, gamma_gen and beta_gen.

Closes github issue gh-2514.

* scipy.misc.doccer: Added the 'inherit_docstring_from' decorator for
  inheriting  docstrings in methods of subclasses.
* scipy.stats.beta_gen:
  * Correctly handle keyword arguments that fix parameters.
  * When both floc and fscale are given, the parameters are estimated by MLE
    (as stated in the docstring). Previously it had been using the method
    of moments.
  * When both floc and fscale are given, an error is raised if any data
    values are not in the open interval (floc, floc+fscale).
* scipy.stats.gamma_gen:
  * Correctly handle the keyword arguments that fix parameters.
  * A regularization term was added in the denominator of the formula for
    estimating the shape parameter a in gamma_gen._fitstart.
* scipy.stats.norm_gen: Implement a 'fit' method that uses the explicit
  formulas for the maximum likelihood estimation of the parameters.
Merge pull request #2519 from WarrenWeckesser/bug-gamma-beta-fit

BUG+ENH: stats:  Improve the 'fit' method of norm_gen, gamma_gen and beta_gen.
Merge pull request #2714 from rgommers/issue-2482-test-rounding

Fix issue 2482, test failures in spatial and stats
TST: Silence some warnings.
TST: Small test optimizations.
TST: Add warning catches for indexing and inv and exp tests.
TST: Add warning catches to tests in sparse.linalg.
TST: remove duplicate with-statement in sparse/tests/test_base.py
Merge branch 'pr/2731' into master.

https://github.com/scipy/scipy/pull/2731
BUG: spatial/qhull: fix memory leak in setlist.pxd
TST: interpolate: add a benchmark for checking if interpnd leaks memory