Replace large timeout (1024*1024*1024) using real-time clock timeout (10 seconds default)

Change SHARED_MEMORY_MAGIC_NUMBER to make sure server/client are using the same version (shared memory)
add --realtimesimulation to physics server (GUI, VR)
remove --G Xcode from build_cmake_pybullet_double.sh

examples/SharedMemory/SharedMemoryPublic.h

@@ -2,6 +2,9 @@
 #define SHARED_MEMORY_PUBLIC_H
 
 #define SHARED_MEMORY_KEY 12347
+///increase the SHARED_MEMORY_MAGIC_NUMBER whenever incompatible changes are made in the structures
+///my convention is year/month/day/rev
+#define SHARED_MEMORY_MAGIC_NUMBER 201702220
 
 enum EnumSharedMemoryClientCommand
 {