Physics runs in a separate thread from rendering in PhysicsServerExample (preliminary)

Improve rendering performance. OpenVR experience is smooth now.
commit needs a bit more testing before pushing in main repo.

test/SharedMemory/test.c

@@ -106,7 +106,7 @@ void testSharedMemory(b3PhysicsClientHandle sm)
 			b3SharedMemoryCommandHandle command = b3LoadUrdfCommandInit(sm, urdfFileName);
 			
             //setting the initial position, orientation and other arguments are optional
-            startPosX =0;
+            startPosX =2;
             startPosY =0;
             startPosZ = 1;
             ret = b3LoadUrdfCommandSetStartPosition(command, startPosX,startPosY,startPosZ);