1.  Reject lines to improve 1D Arc fit RMS:  Orders 89, 90, 100
  --- I wonder if line centroiding is failing in x_templarc
2.  Deal with vignetting at >4000pix in Trace flat
  -- Just blue?
3.  Modify hires_slitflat as Scott suggested (extrapolation)
4.  Worry about scattered light in skysub
5.  Add header to Final files
