Pending improvements to NLSL

*** Remove sbi and sdb from parameters stored with each spectrum
    Re-calculate them based on b0 and range


I. Should allow calculations to be made without data.
  (1) Windows:
      (a) One window for each series element.
      (b) Windows are created by a "series" command or by a "data" command.
          A window is created if nser>nwindw (in series command) or if 
          nspc>nwindw (in data command). Also, windows are deleted by
          series command if nsite<nwindw. 
      (c) New windows are initialized so that they are cascaded onto 
          existing windows. If they are moved or resized, the size
          is retained when the window is destroyed.
      (d) Calculate fvec only for all datapoints available. Check that ndata
          is used for all calculations that do not have data.
      (e) Automatic writing is disabled for all calculations where there is
          no data. An explicit "write" command is required for those 
          calculations. The dataset name will consist of a sequence number
          appended to the user-supplied name.

Case of nser>nspc is almost implemented in lfun. Some way is needed in
lfun to calculate a starting index and length for spectra without data,
in order to store -calc in fvec.

Q's: 
(1) How is the number of points determined when there is no datafile?
   ndata(nspc) is set by datac when file is read in
   ndata(nser) is copied from site 1 when series is set
   Assigning NFIELD a value only works for indices greater than nspc
   nptot -> ndatot (total number of datapoints)

   new parameter: RANGE allows field range to be set

(2) How are multisite scale factors determined when there is no data?

DONE  Update Xwindows routines to accommodate component display
III. Propagate errors in potential coefficients to get errors in order 
     parameters.
IV.  Implement Kolmogorov-Smirnov test
V.   When new data is read in and there is an existing calculated
     spectrum, rescale (and shift?) the calculation to fit the data.

Other minor notes:
  MAXITR in search command not implemented
  Search should report termination criterion (add info to brent call)