message: BUGFIX: fix build with clang9 + cuda-10.2
  Fix build encountered when using the clang9 compiler toolchain
  and cuda-10.2. The compiler was not able to deduce correctly the
  alias for `GridPt`. Redefining the alias inside the class resolved
  the issue.
diff: @@ -210,6 +210,7 @@ public:
  >
  {
  public:
  + using GridPt = typename OctreeLevel::GridPt;
  using iter = BlockIterator< OctreeLevel, IterHelper, DataType>;
  BlockIterator(OctreeLevel* octLevel, bool begin = false)
  