[layers] fix cyclic includes

.gitsuper

@@ -17,7 +17,7 @@ status = 1a3bcab04b011a5d6e44f9983cae6ff89fa695e8 bin (heads/master)
 	+effefc7695eba0c0ca94fff0f93026b86501027e dune-xt-common (heads/master)
 	+3e3f3bf06e21cbbf3c0a559891b44c6f5d987d0f dune-xt-data (heads/master)
 	+f05aa7470ead4150ca7a91894cd2ad77dfcedc46 dune-xt-functions (heads/new-master)
-	+71040d95d7550af919fa507d0bf2dad5c437719c dune-xt-grid (heads/new-master)
+	+2b3d0b6af982c31720849dfe47815fac21cfa0aa dune-xt-grid (heads/new-master)
 	+f6904b69f9a3ee5d45ee824d3b244e59cfed7ff4 dune-xt-la (heads/master)
 	 09d0378f616b94d68bcdd9fc6114813181849ec0 scripts (heads/master)
 commit = 5f5841ee7a2dff290b98845c46262151752189c1
@@ -110,7 +110,7 @@ commit = f05aa7470ead4150ca7a91894cd2ad77dfcedc46
 [submodule.dune-xt-grid]
 remote = git@github.com:dune-community/dune-xt-grid.git
 status = 2424627f0ad5de7e4aaa5e7f48bc2a02414d95a1 .vcsetup (heads/master)
-commit = 71040d95d7550af919fa507d0bf2dad5c437719c
+commit = 2b3d0b6af982c31720849dfe47815fac21cfa0aa
 
 [submodule.dune-xt-la]
 remote = git@github.com:dune-community/dune-xt-la.git

dune/xt/grid/layers.hh

@@ -17,7 +17,6 @@
 
 #include <dune/xt/common/fixed_map.hh>
 #include <dune/xt/grid/type_traits.hh>
-#include <dune/xt/grid/view/periodic.hh>
 #include <dune/xt/grid/view/subdomain/view.hh>
 
 namespace Dune {
@@ -34,6 +33,11 @@ class SubdomainGrid;
 } // namespace DD
 
 
+// forward
+template <class RealGridLayerImp, bool codim_iters_provided>
+class PeriodicGridView;
+
+
 enum class Backends
 {
   view
@@ -237,7 +241,7 @@ template <class GridType, Layers layer, Backends backend, class DdGridType>
 struct Layer<GridType, layer, backend, DdGridType, true>
 {
   using NonPeriodicLayerType = Layer<GridType, layer, backend, DdGridType, false>;
-  using type = XT::Grid::PeriodicGridLayer<typename NonPeriodicLayerType::type>;
+  using type = PeriodicGridView<typename NonPeriodicLayerType::type, false>;
 
   static type create(const GridType& grid,
                      const int subdomain = 0,