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
Fix locations / links in astropy.modeling Sphinx API docs
minor documentation fixes & comments in convolution
Prevent convolution of enormous (>1 GB) arrays unless explicitly
overridden by user.  This is important to catch situations in which
highly asymmetric cubes (e.g., a spectral cube with ndim = [1024,8,8])
are padded to become gigantic (1024**3 pixels, each with 8 bytes... and
you need 4 copies!!!)
need to check for that override parameter...
Exception -> ValueError
add "optional" flags
added a brief note about when 'convolve' is preferable
too much happened in this commit...
1. Rearranged convolve_fft and removed a redundant exception
2. Moved the memory exception before any duplication
3. added (in comment) the formula for total memory used
4. added a test (thanks @astrofrog for the memmap help)
minor change to comments
fixed boolean tests, order of operations, exceedingly slow bigarray test
(np.empty is better than np.memmap for this)
human readable times