avoid memory leaks, even if a the python interpreter exits without calling 'disconnect' on all physics servers

(register a Py_AtExit function that cleans all up), to avoid memory leaks

examples/pybullet/pybullet.c

@@ -1,3 +1,4 @@
+#include "vld.h"
 #include "../SharedMemory/PhysicsClientC_API.h"
 #include "../SharedMemory/PhysicsDirectC_API.h"
 #include "../SharedMemory/SharedMemoryInProcessPhysicsC_API.h"
@@ -398,6 +399,22 @@ static PyObject* pybullet_disconnectPhysicsServer(PyObject* self,
 	return Py_None;
 }
 
+
+void b3pybulletExitFunc()
+{
+	int i;
+	for (i=0;i<MAX_PHYSICS_CLIENTS;i++)
+	{
+		if (sPhysicsClients1[i])
+		{
+			b3DisconnectSharedMemory(sPhysicsClients1[i]);
+			sPhysicsClients1[i] = 0;
+			sNumPhysicsClients--;
+		}
+	}
+}
+
+
 static PyObject* pybullet_saveWorld(PyObject* self, PyObject* args, PyObject* keywds)
 {
 	const char* worldFileName = "";
@@ -5453,6 +5470,10 @@ initpybullet(void)
 	Py_INCREF(SpamError);
 	PyModule_AddObject(m, "error", SpamError);
 
+		
+	Py_AtExit( b3pybulletExitFunc );
+	
+
 #ifdef PYBULLET_USE_NUMPY
 	// Initialize numpy array.
 	import_array();