world coords specifications in FITS headers

[Klaus Banse <kbanse@eso.org>]

Dear Midas users,

    up to now, Midas needed the FITS keywords CDELT1, CDELT2, ...
to build up the descriptors START, STEP of Midas images.
If there were no CDELTi found in the FITS header, STEP was initialized
to 1.0 - which would lead to problems when using world coordinates
with such an image in Midas...

By now, the new standard for world coord specification in FITS has been 
officially adopted.
In short, it proposes to (rather) use the CD matrix for the
specification
of the world coord. system, from which one could compute the CDELTi if
necessary.

The Midas FITS I/O routines have been updated accordingly.
For backwards compatibility we'll still look first for the
keyword CDELTi and only if these are missing we use the CD matrix
to compute the CDELTi.

These changes will be incorporated in the upcoming 03FEB release
of Midas. That's a so-called internal release at ESO but will be
available via our ftp server, as well.

Klaus Banse