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/ExampleBrowser/main.cpp

@@ -19,13 +19,15 @@
 
 #include "LinearMath/btAlignedAllocator.h"
 
+static double gMinUpdateTimeMicroSecs = 1000.;
+
 
 int main(int argc, char* argv[])
 {
 	{
 		b3CommandLineArgs args(argc, argv);
 		b3Clock clock;
-
+		args.GetCmdLineArgument("minUpdateTimeMicroSecs",gMinUpdateTimeMicroSecs);
 
 		ExampleEntriesAll examples;
 		examples.initExampleEntries();
@@ -45,9 +47,18 @@ int main(int argc, char* argv[])
 			do
 			{
 				float deltaTimeInSeconds = clock.getTimeMicroseconds() / 1000000.f;
-				clock.reset();
-				exampleBrowser->update(deltaTimeInSeconds);
-
+				if (deltaTimeInSeconds > 0.1)
+				{
+					deltaTimeInSeconds = 0.1;
+				}
+				if (deltaTimeInSeconds < (gMinUpdateTimeMicroSecs/1e6))
+				{
+					b3Clock::usleep(gMinUpdateTimeMicroSecs/10.);
+				} else
+				{
+					clock.reset();
+					exampleBrowser->update(deltaTimeInSeconds);
+				}
 			} while (!exampleBrowser->requestedExit());
 		}
 		delete exampleBrowser;