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/pybullet/pybullet.c

@@ -497,6 +497,39 @@ static PyObject* pybullet_setRealTimeSimulation(PyObject* self,
   return Py_None;
 }
 
+
+
+static PyObject* pybullet_setInternalSimFlags(PyObject* self,
+                                                PyObject* args) {
+  if (0 == sm) {
+    PyErr_SetString(SpamError, "Not connected to physics server.");
+    return NULL;
+  }
+
+  {
+    int enableRealTimeSimulation = 0;
+    int ret;
+
+    b3SharedMemoryCommandHandle command = b3InitPhysicsParamCommand(sm);
+    b3SharedMemoryStatusHandle statusHandle;
+
+    if (!PyArg_ParseTuple(args, "i", &enableRealTimeSimulation)) {
+      PyErr_SetString(
+          SpamError,
+          "setInternalSimFlags expected a single value (integer).");
+      return NULL;
+    }
+    ret =
+        b3PhysicsParamSetInternalSimFlags(command, enableRealTimeSimulation);
+
+    statusHandle = b3SubmitClientCommandAndWaitStatus(sm, command);
+    // ASSERT_EQ(b3GetStatusType(statusHandle), CMD_CLIENT_COMMAND_COMPLETED);
+  }
+
+  Py_INCREF(Py_None);
+  return Py_None;
+}
+
 // Set the gravity of the world with (x, y, z) arguments
 static PyObject* pybullet_setGravity(PyObject* self, PyObject* args) {
   if (0 == sm) {
@@ -2218,6 +2251,9 @@ static PyMethodDef SpamMethods[] = {
 	"Enable or disable real time simulation (using the real time clock,"
 	" RTC) in the physics server. Expects one integer argument, 0 or 1" },
 
+	{ "setInternalSimFlags", pybullet_setInternalSimFlags, METH_VARARGS,
+	"This is for experimental purposes, use at own risk, magic may or not happen"},
+	
     {"loadURDF", pybullet_loadURDF, METH_VARARGS,
      "Create a multibody by loading a URDF file."},