usage: eyecalwks flag WKSfile [eyecalib_file NPLOT scr_wid scr_hgt smoothms]"
       default:      -1   "xx"       "auto"       0  eyescrwid eyescrhgt 500"

    FLAG: 0 - normal mode"
          1 - remove Y position drift
          2 - smooth X and Y values"
          4 - plot calibration grid"
          8 - plot eye positions"
         16 - don't calculate calibrated eyepos"
         32 - create calibrated ...CALIB.WKS file"
         64 - data already loaded from WKSfile and eyecalib file"
        128 - only read WKSfile -- don't transform data"
        256 - don't look for eyecalib file"

     NPLOT: If plotting, number of eye pos points to plot (0 = all)"