NAME:
  photprmt
 PURPOSE:
  Promote version of a photometry log file to highest version.
 DESCRIPTION:

 CATEGORY:
  File I/O
 CALLING SEQUENCE:
  photprmt,photfile
 INPUTS:

  photfile - File with photometry data.

 OPTIONAL INPUT PARAMETERS:

 KEYWORD INPUT PARAMETERS:
  NEEDBADFLG    - Flag, if set, requires that the bad flag be present in 
                     the photometry file. Ordinarily, a default value of 0
                     or other value is adopted via a user prompt if the flag
                     is not already there. Note that this ONLY applies when 
                     promoting 0.0.
  DEFBADFLAG    - Default to set the bad flag in the photometry file if it is
                     not present. It pre-empts the prompting of the user for
                     the value, and operates silently. This keyword  ignored if
                     NEEDBADFLG is set.  Note that this ONLY applies when 
                     promoting 0.0.
                
 OUTPUTS:

  The photfile is updated to the most recent version.  Not changed if already
    current, or an error is encountered in processing. Prior to overwriting
    the original, a backup copy of the original photfile is made, named
    photfile + '.bak'  so something.log becomes something.log.bak

   The following formats are supported:
   v0.0  The base format with no version line (aka anonymous)
         The version generated by BASPHOTE when /altlog is not specified.
   v1.0  Version line at the start:   PHOTFILE v1.0
         adds sky signal and sky error fields right after maxcnt
   v1.1  Version line at the start:   PHOTFILE v1.1
         adds read noise field right after the gain
         The version now generated by BASPHOTE when /altlog is specified.

 KEYWORD OUTPUT PARAMETERS:

 COMMON BLOCKS:

 SIDE EFFECTS:

 RESTRICTIONS:

 PROCEDURE:

 MODIFICATION HISTORY:
  2000/06/02, Written by Marc W. Buie, Lowell Observatory
  2002/09/03, MWB, changed Str_sep call to strsplit
  2006/04/28, Peter L. Collins, Lowell Observatory
                created PHOTFILE v1.1 for carrying read noise,
                which is effectively defaulted as 0.00.
  2006/5/23,  PLC, added a registration test to prevent invalid
                   promotion of faux 0.0 files
  2006/5/26,  PLC, allow 0.0 to be promoted without a bad flag
                   an option that is suppressed by /NEEDBADFLG
                   and a default supplied by DEFBADFLG (or 0).
  2006/7/14,  PLC, add creation of .bak copy of the original.