Fields of WID2 struct in ts::sff::TraceHeader are not provided for direct
write access.

In order to be compatible with the previous version, the output file is again
defined to be last on the command line.

A new doxygen configuration is provided in the libraries root directory. The
resulting HTML documentation provides interactive links between components of
different libraries.

Attention: The output file now must be specified in front of the input files
on the command line.

- use proper libdatrwxx access for input and output to support different file
  formats
- make use of time series structures which handle the full header

The implementation is not yet finished, and sclaing of results as well as
settings in the file and trace header differ from the previous version.

Provide example of solving a least squares problem.

Fix a type in functions names and set at least one of the elements
differently, such that the result of a transpose operation can become
apparent.

Introduce output operator for two-dimensional array in the example program.