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   Read in output text file generated by MultiVehicleSim
     for use with the PlottingTool.
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   Form:
   d = ReadMVSSimulationFile( fId, fileName )
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   ------
   Inputs
   ------
   fId                          (1)      Id of file to be read
   fileName                     (:)      Optional input string for error messages

   -------
   Outputs
   -------
   d                            (1)      Data structure with the following fields
                                         ( nD  = number of data elements
                                           nSc = number of spacecraft
                                           nT  = number of time points )

        .data                   {1,nSc}  Cell array of (nDxnT) matrices of raw data
        .dataNames              {1,nD}   Cell array of strings of element names
        .dataUnits              {1,nD}   Cell array of strings of element units
        .excluded               {1,:}    Cell array of names of elements not to be displayed
        .groups                 (:)      Array of data structures of grouped elements
                    .name       (:)      String of group name
                    .elements   {1,:}    Cell array of names of elements to be included in group
        .jDEpoch                (1)      Start time of simulation as Julian date
        .scNames                {1,nSc}  Cell array of strings of spacecraft names
        .time                   (1,nT)   Vector of elapsed simulation time in seconds

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