In case there is only one (or no) solution, we can of course reduce
it.
Add setter to change the input parameters
Add test for the MSSM spectrum
Add getters which return the LaTeX name of a particle
Put the Parameter_getter into a separate utilities file.
Add -Wno-unused-local-typedefs to the CXXFLAGS to suppress long
warnings from the Eigen library
Add a spectrum plotter class to the utilities module.
Write the name of the multiplet into one column.  Now the user
can plot the spectrum file via

   plot "MSSM_spectrum.dat" using 1:2:xtic(3)
Plot only the (one-loop) pole masses.  The running tree-level masses
are not really interesting.