NAME:
  hstwcspdf
 PURPOSE:   (one line only)
  Generate the final PDF from the joint constraints for all the good stars
 DESCRIPTION:
 CATEGORY:
  Astrometry
 CALLING SEQUENCE:
  hstwcspdf,filestem
 INPUTS:
  filestem - String that is used to select a set of file for processing.
             The search string for files will be
               filestem+'*_flc.fits.gz'
 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
 OUTPUTS:
 KEYWORD OUTPUT PARAMETERS:
 CONFIGURATION: (optional, overrides xtrack.in)
   File: config.ini
   [global]
     subdir   - naem of sub-directory  added to base path to find data
     filetype - type of file to read ('flt' or 'flc'), default='flc'
   [ddir]   - section to list potential root directories to find data
     XXX - 
       XXX is a unique string (eg., D01)
        is a directory path
       for additional details see getddir.pro
 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
 PROCEDURE:
 MODIFICATION HISTORY:
  2020/07/01, Written by Marc W. Buie, Southwest Research Institute