Log Message:
update to 2.4.0
changes:
-Added some HDU methods for metadata
-Enhanced the section class to allow reading non-contiguous image data
-Added a verify keyword argument to the pyfits.append function
-Added a new optional keyword arguments disable_image_compression
 and do_not_scale_image_data to pyfits.open
-Checksum support now correctly conforms to the FITS standard
-bugfixes