message: impose out of bounds penalty if ligand is outside cnn box,  keep
  reference frame fixed during minimization, some code cleanup, note I
  needed to make igrid non-const to allow updating of grid center
diff: @@ -125,6 +125,10 @@ public:
  mem_lig.center = center;
  }
  + vec getCenter() const {
  + return mem_lig.center;
  + }
  +
  //set in memory buffer
  template<typename Atom, typename Vec3>
  void setLigand(const vector<Atom>& ligand, const vector<Vec3>& coords, bool calcCenter=true)
  