Merge branch 'fix/headercheck_PN_properties' into 'master'

Added 2pnc model, which includes properties. Fixes, Labels link

See merge request !3806

test/porenetwork/2pnc/problem.hh

@@ -14,8 +14,9 @@
 
 #include <dumux/common/boundarytypes.hh>
 #include <dumux/common/parameters.hh>
-#include <dumux/porousmediumflow/problem.hh>
 #include <dumux/material/components/air.hh>
+#include <dumux/porousmediumflow/problem.hh>
+#include <dumux/porenetwork/2pnc/model.hh>
 
 namespace Dumux {