itertools.izip_longest is not in Python 3

git-svn-id: http://svn6.assembla.com/svn/pyfits/branches/3.2-stable@2692 ed100bfc-0583-0410-97f2-c26b58777a21
If the provided 'fileobj' is actually just a string (for a file path) it should be treated as 'closed'

git-svn-id: http://svn6.assembla.com/svn/pyfits/branches/3.2-stable@2696 ed100bfc-0583-0410-97f2-c26b58777a21
Add izip_longest implementation for python 2.5

git-svn-id: http://svn6.assembla.com/svn/pyfits/branches/3.2-stable@2704 ed100bfc-0583-0410-97f2-c26b58777a21
Oops--no six in this branch

git-svn-id: http://svn6.assembla.com/svn/pyfits/branches/3.2-stable@2706 ed100bfc-0583-0410-97f2-c26b58777a21