pybullet, more robust multi-server connections

Windows shared memory: allow to use custom key.
Improve GUI performance on Windows, submit letters in text as a batch (fewer draw-calls)
quadruped.py: first try to connect to SHARED_MEMORY, if it fails (<0) use GUI
increase Chrome about://tracing json export capacity (press 'p' in Example Browser)
UDP physics server: add --port and --sharedMemoryKey command-line arguments
PhysicsServerExample: add --sharedMemoryKey command-line option (for VR example too)
ExampleBrowser: sleep a few milliseconds if rendering is too fast, use --minUpdateTimeMicroSecs=0 to disable

examples/StandaloneMain/main_opengl_single_example.cpp

@@ -99,6 +99,7 @@ int main(int argc, char* argv[])
         app->m_instancingRenderer->updateCamera(app->getUpAxis());
 
 		btScalar dtSec = btScalar(clock.getTimeInSeconds());
+		dtSec = b3Min(dtSec,0.1);
 		example->stepSimulation(dtSec);
 	  	clock.reset();