[fitswcs] WCS announcements

[Doug Mink]

Some comments on WCSLIB 3.0:

1.  Changingthe format of subroutine names from *fwd and *rev to
    *x2y and *y2x eliminates confusion.  I have always had to read
    the code to figure out which was which.

2.  Thanks for adding memory management.  I've already implemented
    it on top of WCSLIB in WCSTools, but this will make dealing with
    the new vectors easier.
    
3.  Will wcsini() recognized CDi_j and CROTAi as legitimate WCS keywords?
    If it doesn't, hiding piximg and imgpix makes it harder to process
    the CDi_j keywords which are present in a huge amount of data.  We
    have found that it is not straightforward to go from CD to CDELT and
    rotation, but it is easy to go to piximg and imgpix.  There might need
    to be an alternate version of linset() or additional arguments--I
    currently pass my equivalent program multiple parallel arguments
    which are null pointers if unused.

4.  Maintaining a single code base by wrapping the C code with Fortran
    should be easier.  That's how I do it now, and it works well.

Thanks for making the headers available for comment.

-Doug Mink