Convert MssmSofsusy into a template class

  template<class SoftPars>
  class Softsusy: public SoftPars, public AltEwsbMssm {};

and add a typedef

  typedef Softsusy<SoftParsMssm> MssmSoftsusy;

Now we are prepared to inherit NmssmSoftsusy from Softsusy in
the form

  class NmssmSoftsusy: public SoftSusy<SoftParsNmssm> {};

to reuse MSSM code.