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Spectra extraction (CCD to datacube)

-mask none Input extraction mask
-in none Input frame to be extracted (preprocessed, in e-)
-out none Output datacube
-width 5 Extraction window full-width [px]
-cal none Calibration frame
-weighted Weighted summation
-lens -1 Single lens extraction
-overlap De-polluted summation
-offset NULL Calibration offset (manual)
-cal2 NULL 2nd calibration frame
-local Local adjustment to mask positions
-linfit Linear fit (not fully tested)
-verbose Verbose output
-variance Use [signal] and [variance] extensions of input frame (default: compute var on-the-fly)
Error status
In single-lens debug extraction, a residual map of the extraction process can be computed from the dbg_ext_extract_spec debug cube, by converting the signal (input frame) and the variance (model) extensions of the cube to 2D-frames, and subtracting them, e.g.,
 export_spec -in dbg_ext_xdisp.tig -out lens113_2D  -longslit -lcol NO,LBDA
 export_spec -in dbg_ext_xdisp.tig -out lens113F_2D -longslit -lcol NO,LBDA -noise 

Expand the domain of validity of the Chebyshev expansion for sigma (and dx?) from the useful wavelength range [lbda_inf,lbda_sup] to the total wavelength range [lbda_inf_tot,lbda_sup_tot] (requires changes in create_mask and snifs_instrument.h) (see comment "get lbda = f(yd)")

CAREFULLY CHECK THE OPTIMAL EXTRACTION (signal and variance). In particular, use the variance extension during the optimal extraction. One could also have a look at Khmil & Surdej 2002 (optimal extraction with maximum entropy).

Implement option -linfit

The spatial coordinates still have to be computed.

For the two-pass multi-order optimal extraction, add an option -restore to extract pre-restore_frame (i.e. without the final wavelength-rebin and extracted on the full wavelength domain).

There might be a bug (potential SEGFAULT) in the computation of fitting window limits i1,i2,... in Sauron.

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