[PL] Pass integration order to Process.

Remove default value.

ProcessLib/Process.cpp

@@ -22,6 +22,7 @@ Process::Process(
     MeshLib::Mesh& mesh,
     std::unique_ptr<ProcessLib::AbstractJacobianAssembler>&& jacobian_assembler,
     std::vector<std::unique_ptr<ParameterBase>> const& parameters,
+    unsigned const integration_order,
     std::vector<std::reference_wrapper<ProcessVariable>>&& process_variables,
     SecondaryVariableCollection&& secondary_variables,
     NumLib::NamedFunctionCaller&& named_function_caller)
@@ -30,6 +31,7 @@ Process::Process(
       _named_function_caller(std::move(named_function_caller)),
       _global_assembler(std::move(jacobian_assembler)),
       _process_variables(std::move(process_variables)),
+      _integration_order(integration_order),
       _boundary_conditions(parameters)
 {
 }

ProcessLib/Process.h

@@ -40,15 +40,14 @@ public:
     using NonlinearSolver = NumLib::NonlinearSolverBase;
     using TimeDiscretization = NumLib::TimeDiscretization;
 
-    Process(
-        MeshLib::Mesh& mesh,
-        std::unique_ptr<AbstractJacobianAssembler>&&
-            jacobian_assembler,
-        std::vector<std::unique_ptr<ParameterBase>> const& parameters,
-        std::vector<std::reference_wrapper<ProcessVariable>>&&
-            process_variables,
-        SecondaryVariableCollection&& secondary_variables,
-        NumLib::NamedFunctionCaller&& named_function_caller);
+    Process(MeshLib::Mesh& mesh,
+            std::unique_ptr<AbstractJacobianAssembler>&& jacobian_assembler,
+            std::vector<std::unique_ptr<ParameterBase>> const& parameters,
+            unsigned const integration_order,
+            std::vector<std::reference_wrapper<ProcessVariable>>&&
+                process_variables,
+            SecondaryVariableCollection&& secondary_variables,
+            NumLib::NamedFunctionCaller&& named_function_caller);
 
     /// Preprocessing before starting assembly for new timestep.
     void preTimestep(GlobalVector const& x, const double t,
@@ -183,7 +182,7 @@ protected:
     VectorMatrixAssembler _global_assembler;
 
 private:
-    unsigned const _integration_order = 2;
+    unsigned const _integration_order;
     GlobalSparsityPattern _sparsity_pattern;
 
     /// Variables used by this process.