KneeSimulator: Made more FDK options optional with ??= operator.

Author: mdabt

Application/Examples/KneeSimulator/Model/AnyKneeSimulator.any

@@ -19,7 +19,7 @@ Main = {
 
   AnyBodyStudy KneeSimulatorStudy = {
     // A low kinematic tolerance will help FDK optimization to converge
-    Kinematics.KinematicTol = 1e-8;
+    Kinematics.KinematicTol ??= 1e-8;
 
     AnyFolder& Parameters = .Parameters; 
     AnyFolder& Model = .Model;
@@ -46,8 +46,8 @@ Main = {
     InverseDynamics.ForceDepKin.LocalSearchMaxSteps ??= 15; // Reduced from default 25. Speeds up convergense.
 
 
-    InverseDynamics.ForceDepKin.MaxNewtonStep = FDK_MaxNewtonStep;       
-    InverseDynamics.ForceDepKin.LocalSearchOnOff = FDK_LocalSearchOnOff;  
+    InverseDynamics.ForceDepKin.MaxNewtonStep ??= FDK_MaxNewtonStep;       
+    InverseDynamics.ForceDepKin.LocalSearchOnOff ??= FDK_LocalSearchOnOff;  
 
     #ifdef TOOLS_MODELUTILITIES_VIDEO_CAMERACLASSTEMPLATE
     // Include functions to generate a video: