- check that the result of fileno($fh) is defined rather than simply

 - check that the result of fileno($fh) is defined rather than simply
   true when read() or write() is supplied with an fh parameter.
   http://rt.cpan.org/Ticket/Display.html?id=35139

 - i_scale_axis() wasn't checking the result of i_img_new_ch()
   resulting in a SIGSEGV when attempting to scale an image to a size
   too large to fit in memory.  This is a NULL pointer access issue,
   not a buffer overflow.
   Added a check for the failure.
   scale_calculate() (and hence scale()) will now fail if any of the
   scale size parameters are a reference.
   http://rt.cpan.org/Ticket/Display.html?id=35172