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.

examples/OpenGLWindow/SimpleOpenGL2Renderer.h

@@ -68,6 +68,8 @@ struct SimpleOpenGL2Renderer : public CommonRenderInterface
     
     virtual void writeSingleInstanceTransformToCPU(const double* position, const double* orientation, int srcIndex);
     
+    virtual int getTotalNumInstances() const;
+    
     virtual void writeTransforms();
     
     virtual void drawLine(const double from[4], const double to[4], const double color[4], double lineWidth);
@@ -82,6 +84,7 @@ struct SimpleOpenGL2Renderer : public CommonRenderInterface
 
 	virtual void clearZBuffer();
 
+
 	virtual struct	GLInstanceRendererInternalData* getInternalData()
 	{
 		return 0;