Clang format 8
This applies clang-format-8 to dune-xt. For some reason, there are some changes compared to clang-format-6. I tried to adjust the config, but that only introduced more changes.
This applies clang-format-8 to dune-xt. For some reason, there are some changes compared to clang-format-6. I tried to adjust the config, but that only introduced more changes.