We must not wrap the latex particle names, as it might lead to
problems.  For example, this is not well-formed C/C++

  chat* x = "\\x^
     2";
Add array of particle multiplicities (= multiplet length)
Use a valarray for the particle masses, because an Eigen array is
simply not necessary and might cause some unwanted dependency and
overhead.
Add tests for the Yukawa couplings after the iteration
Add tests for the trilinear couplings.  Here TYd(2,2) (3rd family)
shows the biggest deviation of ~1.1%
Do not calculate the SM pole masses by default to gain some speed.
Simplify the spectrum filler a bit
Plot SM particle pole masses only if the have been calculated