NAME: closeps
PURPOSE: Close the Postscript mode
CALLING SEQUENCE: closeps
KEYWORD PARAMETERS:
INFOWIDGET: A long integer giving the id of the information
widget (created by openps) that we have de destroy at
the end of closeps (when the postscript is done)
COMMON BLOCKS: cm_4ps
SIDE EFFECTS: when archive_ps ne 0, we add the name and the date
at the bottom left corner of the postcript page. If the
postscript is called idl.ps we change its name to number.ps
(number automatically found to be 1 larger that any of the
existing ps file)