Standardize how Python version checking is done.
Add changes to io.fits
Make `@deprecated` decorator work for classes.
Fix pickling issues with class deprecation.  Fix Python 2.6 bug.
Implement `InheritDocstrings` metaclass to automatically inherit
docstrings on methods from those in the base class.
Add warning about multiple inheritance.
Move io.votable to use InheritDocstrings
Move units to use InheritDocstrings
Inherit ndarray docstrings in Quantity
Merge pull request #2159 from mdboom/misc/docstring-inheritance

Automatically inherit docstrings from base classes
Fix changelog heading
Removed empty placeholder headings under the 0.3.1 section
Released v0.3.1
A couple small fixes to the release procedures made while making the v0.3.1 release.  First --distribute should not be used with virtualenv anymore, as distribute is deprecated. I also removed the mention of backport-* labels, the use of which seems to have been abandoned for now (it may come back in the future but for now it is not really used)
Use of deprecated 'key' member in error message

When parsing invalid card, the error itself raises an error due to use of deprecated self.key.
Merge pull request #2175 from bogdanni/patch-1

Use of deprecated 'key' member in error message
distance > 0
now with optional kwarg allow_negative
added test of new kwarg
added note in coordinates docs about negative distances