Merge branch 'fix/dune_deprecated_macro' into 'master'

Replace DUNE_DEPRECATED by [[deprecated]]

See merge request !92

dune/gfe/riemannianpnsolver.hh

@@ -89,7 +89,8 @@ public:
 
     void solve();
 
-    void setInitialSolution(const SolutionType& x) DUNE_DEPRECATED {
+    [[deprecated]] 
+    void setInitialSolution(const SolutionType& x) {
         x_ = x;
     }
 

dune/gfe/riemanniantrsolver.hh

@@ -145,7 +145,8 @@ public:
 
     void solve();
 
-    void setInitialSolution(const SolutionType& x) DUNE_DEPRECATED {
+    [[deprecated]]
+    void setInitialSolution(const SolutionType& x) {
         x_ = x;
     }