FIxed #6513 -- Handle overflows better in the floatformat filter. It's not

possible to test this automatically everywhere due to differing representations
on different platforms. Manual testing confirms it works, though.

Thanks, Karen Tracey.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@7336 bcc190cf-cafb-0310-a4f2-bffc1f526a37