NAME:
    qhyprop
 PURPOSE:   (one line only)
    Return QHY camera properties
 DESCRIPTION:
    This tool provides a way to connect header and setting information
      to more useful fundamental properties of the image data.
 CATEGORY:
  Miscellaneous
 CALLING SEQUENCE:
    qhyprop, setting, gain, rdnoise, dynrng, fullwell
 INPUTS:
    setting : GAIN setting from SharpCap, valid range is 0-400 but is
                validated.
 OPTIONAL INPUT PARAMETERS:
 KEYWORD INPUT PARAMETERS:
    BIT12 = Return 12-bit gain values instead of scaling to 16-bit
              both refer to 12-bit data conversions but the default
              is to bit shift to the 12-bit data by 4 bits making it
              appear to "fill" a 16-bit value.  This introduces an
              apparent change in gain due to the bit shift (16x).
              Set this keyword to avoid the extra factor of 16.
 OUTPUTS:
    gain     : Camera gain [e-/ADU]
    rdnoise  : Camera read noise [e-]
    dynrng   : Camera dynamic range [QHY units]
    fullwell : Camera full well capacity [e-]
 KEYWORD OUTPUT PARAMETERS:
 CONFIGURATION:
 COMMON BLOCKS:
 SIDE EFFECTS:
 RESTRICTIONS:
    Only the QHY174M-GPS camera is supported at the moment and this will
      remain the default into the future with other cameras added through
      the use of keywords as needed.
 PROCEDURE:
    Camera properties are inferred from plots at:
    https://www.qhyccd.com/index.php?m=content&c=index&a=show&catid=94&id=46&cut=1.
    Outputs are linearly interpolated from the camera properties,
    which are currently read by eye, except for the gain. The full
    well capacity in particular is not trustworthy when SETTING>250. 
    If SETTING is input as a scalar then the outputs are scalars; 
    otherwise, they're vectors with the same length as SETTING.

 MODIFICATION HISTORY:
    Written by Brian Keeney, SwRI, 2021/01/15
    2022/03/08, BK, Modified to remove dependence on external files