NAME:
  psfgen
 PURPOSE:   (one line only)
  Generate PSF files for a set of images
 DESCRIPTION:

 CATEGORY:
  CCD data processing
 CALLING SEQUENCE:
  psfgen,root
 INPUTS:
  root       :String, the date when observations are taken (YYMMDD)
 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
  IMDIR      :The path to the image data (default=current directory)
  OVERWRITE  : Flag, if set will overwrite existing PSF files.  The default
                is to skip processing images that already have a PSF.
  PSFDIR     :The directory where the output PSF files are to be written.
                The default is SRCDIR+'/psf'
  SRCDIR     :The path to the source lists (default=current directory)
                These files are normally generated by findsrc.
  QUIET      :Flag, suppress all chatty printed output.
  VIEWIT     ;Flag, set to look at the psf header (and subheader)
 KEYWORD OUTPUT PARAMETERS:
 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
 PROCEDURE:
 MODIFICATION HISTORY:
  2004/07/13, Written by Maureen Teyssier, REU Lowell Observatory
  2004/07/16, MWB, incorporated into the master library
  2004/08/13, MWB, fixed bug with psfdir non-default operation