Add muntidim sbg input generation.

[joaquinffernandez]

Currently the input for SBG binary eval only handles one dimension. Extend with the previous code for multi--dim intervals.

void GenerateSBGInput::addDims(size_t max_dim, size_t exp_dim, SBG::MultiInterval& intervals, int offset)
{
  if (max_dim > exp_dim) {
    for (size_t i = exp_dim; i < max_dim; i++) {
      Interval interval(offset, 1, offset);
      intervals.addInter(interval);
    }
  }      
}

void GenerateSBGInput::addDims(size_t max_dim, size_t exp_dim, ORD_REALS& constant, ORD_REALS& slope)
{
  ORD_REALS::iterator constant_it = constant.end();
  ORD_REALS::iterator slope_it = slope.end();
  if (max_dim > exp_dim) {
    for (size_t i = exp_dim; i < max_dim; i++) {
      constant_it = constant.insert(constant_it, 0);
      slope_it = slope.insert(slope_it, 0);
    }
  }
}

int GenerateSBGInput::generatePWLMaps(Expression exp, int offset, std::string eq_id, size_t max_dim, IndexList dom, int edge_id)
{
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.
.
  if (indexes.empty()) { // Scalar variable.
    addOffset(edge_id, "M1", 0, node_id);
    _m1_slopes.push_back(1);
    addDims(max_dim, 1, constant_pwl_map_u, slope_pwl_map_u);
  } else { 
    addDims(max_dim, indexes.size(), constant_pwl_map_u, slope_pwl_map_u);
  }
  for (const auto& idx : dom) {
    Real set_vertex_init =  getMin(idx);
    addOffset(edge_id, "M2", 0, eq_node_id);
  }
  if (dom.empty()) { // Scalar variable.
    addOffset(edge_id, "M2", 0, eq_node_id);
    addDims(max_dim, 1, constant_pwl_map_u, slope_pwl_map_u);
  } else { 
    addDims(max_dim, dom.minElem().size(), constant_pwl_map_eqs, slope_pwl_map_eqs);
  }
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.
.
}