Feature/interpolation

Interpolation between grids, initial version. Added traversal over irregular elements and gitlabci tests

src/hierarchiciterator.cc

@@ -4,6 +4,8 @@
 # include "config.h"
 #endif
 
+#if DUNE_HAVE_CXX_VARIANT
+
 #include <iostream>
 #include <dune/common/parallel/mpihelper.hh> // An initializer of MPI
 #include <dune/common/exceptions.hh> // We use exceptions
@@ -53,6 +55,7 @@ int main(int argc, char** argv)
   grid.globalRefine(4);
 
   printGrid(grid.levelGridView(2), grid.leafGridView());
-
 #endif
 }
+
+#endif // DUNE_HAVE_CXX_VARIANT
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