change default from np.median to np.ma.median
Fix how terminal size is handled in table.pprint.
Fix #2685.
Change entrt in CHANGES.rst according to comment on github
Address feedback from @taldcroft.
Fix up CHANGES
Set max_lines and max_width to "nothing" in the config file.
Fixes to wcs/test_extension.py

If compilation of the test extension fails, mark the test as skipped,
since it probably just indicates the user doesn't have a working
compilation environment.

Don't ever skip on Travis, since a failure there indicates something
more serious.
Orthogonal to this PR, but my Sphinx was throwing up a warning from there not being a linebreak here.
A bit of other miscellaneous cleanup not related to astropy-helpers
Discussion of astropy-helpers in many places where appropriate. Especially in the docs guide since all the sphinx extensions now live in astropy-helpers.  Also links to APE 4 in several places where it describes astropy-helpers usage
Merge pull request #2582 from hamogu/sigmaclip

sigma_clip: change default from np.median to np.ma.median
Make representations sub-classable and demonstrate with Wrap180 test
Add section on configuration in deprecation/backwards-incompatible changes
Added Quantity section to what's new
Re-wrote intro and added statistics of issues/PRs/contributors

The stats came from the script at https://gist.github.com/eteq/9faf252ec8aa41188dcb
Various what's new tweaks
minor typo fixes/updates for astropy-helper doc changes
Merge pull request #2545 from embray/docs/astropy-helpers

Includes an additional commit by @eteq added manually
Merge pull request #2691 from taldcroft/subclassable-representations

Make representations sub-classable and demonstrate with Wrap180 test