[Cleanup] Do away with unnecessary copies

src/state/ageinglawstateupdater.cc

@@ -2,8 +2,8 @@
 
 template <class ScalarVector, class Vector>
 AgeingLawStateUpdater<ScalarVector, Vector>::AgeingLawStateUpdater(
-    ScalarVector _alpha_initial, Dune::BitSetVector<1> const &_nodes, double _L,
-    double _V0)
+    ScalarVector const &_alpha_initial, Dune::BitSetVector<1> const &_nodes,
+    double _L, double _V0)
     : alpha(_alpha_initial), nodes(_nodes), L(_L), V0(_V0) {}
 
 template <class ScalarVector, class Vector>

src/state/ageinglawstateupdater.hh

@@ -7,7 +7,7 @@
 template <class ScalarVector, class Vector>
 class AgeingLawStateUpdater : public StateUpdater<ScalarVector, Vector> {
 public:
-  AgeingLawStateUpdater(ScalarVector _alpha_initial,
+  AgeingLawStateUpdater(ScalarVector const &_alpha_initial,
                         Dune::BitSetVector<1> const &_nodes, double _L,
                         double _V0);
 

src/state/sliplawstateupdater.cc

@@ -2,8 +2,8 @@
 
 template <class ScalarVector, class Vector>
 SlipLawStateUpdater<ScalarVector, Vector>::SlipLawStateUpdater(
-    ScalarVector _alpha_initial, Dune::BitSetVector<1> const &_nodes, double _L,
-    double _V0)
+    ScalarVector const &_alpha_initial, Dune::BitSetVector<1> const &_nodes,
+    double _L, double _V0)
     : alpha(_alpha_initial), nodes(_nodes), L(_L), V0(_V0) {}
 
 template <class ScalarVector, class Vector>

src/state/sliplawstateupdater.hh

@@ -7,7 +7,7 @@
 template <class ScalarVector, class Vector>
 class SlipLawStateUpdater : public StateUpdater<ScalarVector, Vector> {
 public:
-  SlipLawStateUpdater(ScalarVector _alpha_initial,
+  SlipLawStateUpdater(ScalarVector const &_alpha_initial,
                       Dune::BitSetVector<1> const &_nodes, double _L,
                       double _V0);