[Cleanup] Use the override keyword everywhere

src/rate/backward_euler.hh

@@ -13,7 +13,8 @@ class BackwardEuler : public RateUpdater<Vector, Matrix, Function, dim> {
              Matrix &) override;
   void postProcess(Vector const &) override;
 
-  std::shared_ptr<RateUpdater<Vector, Matrix, Function, dim>> clone() const;
+  std::shared_ptr<RateUpdater<Vector, Matrix, Function, dim>> clone()
+      const override;
 
 private:
 };

src/rate/newmark.hh

@@ -13,6 +13,7 @@ class Newmark : public RateUpdater<Vector, Matrix, Function, dim> {
              Matrix &) override;
   void postProcess(Vector const &) override;
 
-  std::shared_ptr<RateUpdater<Vector, Matrix, Function, dim>> clone() const;
+  std::shared_ptr<RateUpdater<Vector, Matrix, Function, dim>> clone()
+      const override;
 };
 #endif

src/state/ageinglawstateupdater.hh

@@ -15,7 +15,7 @@ class AgeingLawStateUpdater : public StateUpdater<ScalarVector, Vector> {
   void solve(Vector const &velocity_field) override;
   void extractAlpha(ScalarVector &) override;
 
-  std::shared_ptr<StateUpdater<ScalarVector, Vector>> clone() const;
+  std::shared_ptr<StateUpdater<ScalarVector, Vector>> clone() const override;
 
 private:
   ScalarVector alpha_o;

src/state/sliplawstateupdater.hh

@@ -15,7 +15,7 @@ class SlipLawStateUpdater : public StateUpdater<ScalarVector, Vector> {
   void solve(Vector const &velocity_field) override;
   void extractAlpha(ScalarVector &) override;
 
-  std::shared_ptr<StateUpdater<ScalarVector, Vector>> clone() const;
+  std::shared_ptr<StateUpdater<ScalarVector, Vector>> clone() const override;
 
 private:
   ScalarVector alpha_o;