message: Slight optimization in quest ImplicitGrid
diff: @@ -231,8 +231,8 @@ public:
  bbox.expand(m_expansionFactor);
  - const GridCell lowerCell = m_lattice.gridCell( bbox.getMin() );
  - const GridCell upperCell = m_lattice.gridCell( bbox.getMax() );
  + const GridCell& lowerCell = m_lattice.gridCell( bbox.getMin() );
  + const GridCell& upperCell = m_lattice.gridCell( bbox.getMax() );
  for(int i=0 ; i< NDIMS ; ++i)
  {
  @@ -295,8 +295,8 @@ public:
  if(!m_initialized || !m_bb.intersectsWith(box) )
  return BitsetType(0);
  - const GridCell lowerCell = m_lattice.gridCell(box.getMin());
  - const GridCell upperCell = m_lattice.gridCell(box.getMax());
  + const GridCell& lowerCell = m_lattice.gridCell(box.getMin());
  + const GridCell& upperCell = m_lattice.gridCell(box.getMax());
  BitsetType bits = getBitsInRange(0, lowerCell[0], upperCell[0]);
  @@ -402,8 +402,8 @@ private:
  {
  // Note: Need to clamp the gridCell ranges since the input box boundaries
  // are not restricted to the implicit grid's bounding box
  - lower = axom::utilities::clampVal(lower, 0, highestBin(dim));
  - upper = axom::utilities::clampVal(upper, 0, highestBin(dim));
  + lower = axom::utilities::clampLower(lower, IndexType() );
  + upper = axom::utilities::clampUpper(upper, highestBin(dim));
  BitsetType bits = m_binData[dim][lower];
  for(int i = lower+1 ; i<= upper ; ++i)
  