jani -- get expression manager signature now looks more like prism -- get (expression) manager

src/storm/storage/jani/Model.cpp

@@ -689,11 +689,7 @@ namespace storm {
             return false;
         }
         
-        storm::expressions::ExpressionManager& Model::getExpressionManager() {
-            return *expressionManager;
-        }
-        
-        storm::expressions::ExpressionManager const& Model::getExpressionManager() const {
+        storm::expressions::ExpressionManager& Model::getExpressionManager() const {
             return *expressionManager;
         }
 

src/storm/storage/jani/Model.h

@@ -228,12 +228,7 @@ namespace storm {
             /*!
              * Retrieves the manager responsible for the expressions in the JANI model.
              */
-            storm::expressions::ExpressionManager& getExpressionManager();
-
-            /*!
-             * Retrieves the manager responsible for the expressions in the JANI model.
-             */
-            storm::expressions::ExpressionManager const& getExpressionManager() const;
+            storm::expressions::ExpressionManager& getExpressionManager() const;
 
             /*!
              * Adds the given automaton to the automata of this model.