Collect generic properties for non-bonded interaction in a new type

[KaiSzuttor]

This type would hold the values for the cutoff, the offset and the shift for a given interaction.

An implementation could look like this:

template <class Inter> struct CentralPotential {
   using value_type = typename Inter::value_type;

   value_type m_cutoff;
   value_type m_offset;
   value_type m_shift;
   Inter m_inter;

   CentralPotential(value_type cutoff, value_type offset, value_type shift)
       : m_cutoff(cutoff), m_offset(offset), m_shift(shift){};

   bool within_inter_range(value_type r) const {
     auto const r_eff = r - m_offset;
     return r_eff <= m_cutoff and r_eff >= 0.0;
   }

   value_type energy(value_type r) const {
     return within_inter_range(r) ? m_inter.energy(r - m_offset) + m_shift
                                  : value_type{};
   }

   Utils::Vector<value_type, 3>
   force(value_type r, Utils::Vector<value_type, 3> const &r12) const {
     return within_inter_range(r) ? m_inter.force(r - m_offset, r12)
                                  : Utils::Vector<value_type, 3>{};
   }

   value_type cutoff() const { return m_cutoff; }
 };