Added explicit datalink_cleanup to all demo applications.

Moved bip_cleanup() to port specific files.
This works better for bacnet-stack DLLs.

bacnet-stack/demo/iamrouter/main.c

@@ -146,6 +146,7 @@ int main(
     Init_Service_Handlers();
     address_init();
     dlenv_init();
+    atexit(datalink_cleanup);
     /* send the request */
     Send_I_Am_Router_To_Network(Target_Router_Networks);