Removed the ._name and ._extver internal attributes entirely; that data is now managed mainly just by the HDU's header itself.  Replacing the HDU's header with an entirely different header may change its name, which is a possible change in behavior, albeit an uncommon one.

git-svn-id: http://svn6.assembla.com/svn/pyfits/trunk@2198 ed100bfc-0583-0410-97f2-c26b58777a21
A changelog entry for ticket #185.

git-svn-id: http://svn6.assembla.com/svn/pyfits/trunk@2199 ed100bfc-0583-0410-97f2-c26b58777a21