added b3PhysicsParamSetInternalSimFlags command, and pybullet setInternalSimFlags API.

//Use at own risk: magic things may or my not happen when calling this API.

This allows to enable/disable robot assets (samurai world, gripper, KUKA robot etc) in Physics Server (and App_PhysicsServerVR etc)
1 = create robot assets
2 = create experimental box-vr-gui

Add optional command-line parameter for App_PhysicsServerVR, --norobotassets, to start with an empty world, no assets in VR (no gripper, no kuka)

examples/SharedMemory/SharedMemoryCommands.h

@@ -238,9 +238,16 @@ enum EnumSimParamUpdateFlags
 	SIM_PARAM_UPDATE_NUM_SOLVER_ITERATIONS=4,	
 	SIM_PARAM_UPDATE_NUM_SIMULATION_SUB_STEPS=8,
 	SIM_PARAM_UPDATE_REAL_TIME_SIMULATION = 16,
-	SIM_PARAM_UPDATE_DEFAULT_CONTACT_ERP=32
+	SIM_PARAM_UPDATE_DEFAULT_CONTACT_ERP=32,
+	SIM_PARAM_UPDATE_INTERNAL_SIMULATION_FLAGS=64
 };
 
+enum EnumSimParamInternalSimFlags
+{
+	SIM_PARAM_INTERNAL_CREATE_ROBOT_ASSETS=1,
+};
+
+
 ///Controlling a robot involves sending the desired state to its joint motor controllers.
 ///The control mode determines the state variables used for motor control.
 struct SendPhysicsSimulationParameters
@@ -250,6 +257,7 @@ struct SendPhysicsSimulationParameters
 	int m_numSimulationSubSteps;
 	int m_numSolverIterations;
 	bool m_allowRealTimeSimulation;
+	int m_internalSimFlags;
 	double m_defaultContactERP;
 };