9096a66efa99b5111aeaf7b3f9e2bb47a1c467f8 introduced a change to how
FITS_rec objects are copied, which involved doing a deepcopy of its
__dict__.  Sometimes a FITS_rec could have a reference to its underlying
file in the ._file attribute, but file objects can't be copied in
Python.  In Python 2 this fails silently, but in Python 3 it blows up
(somehow I never tested this change in Python 3).

Fortunately back in 0d2cb28cd0017f53225b1733b72a77d9c4f870db I did some
refactoring that made it unnecessary for FITS_rec objects to have an
explicit reference to the file object at all, so removing that fixed the
problem and cleaned up some code rot to boot.

git-svn-id: http://svn6.assembla.com/svn/pyfits/trunk@2337 ed100bfc-0583-0410-97f2-c26b58777a21