GridPtr can also read gmsh files and then handle the load balance of user data.

This MR adds the ability of reading gmsh files to the GridPtr class. This needs testing by some gmsh users.

dune/grid/io/file/dgfparser/test/CMakeLists.txt

@@ -29,3 +29,8 @@ dune_add_test(NAME test-dgf-ug
               SOURCES test-dgf-ug.cc
               COMPILE_DEFINITIONS DUNE_GRID_EXAMPLE_GRIDS_PATH=\"${PROJECT_SOURCE_DIR}/doc/grids/\"
               CMAKE_GUARD dune-uggrid_FOUND)
+
+dune_add_test(NAME test-dgf-gmsh-ug
+              SOURCES test-dgf-ug.cc
+              COMPILE_DEFINITIONS DUNE_GRID_EXAMPLE_GRIDS_PATH=\"${PROJECT_SOURCE_DIR}/doc/grids/\" DGFTEST_USE_GMSH=1
+              CMAKE_GUARD dune-uggrid_FOUND)