Enable the exit menu, which will reset the machine.

A debatable decision, ctrl+shift+esc works anyway, and the menu with
confirmation dialog needs about 200 bytes.
diff --git a/contiki-cpc/arch/crt0.s b/contiki-cpc/arch/crt0.s
index f5608ce..da8bf56 100644
--- a/contiki-cpc/arch/crt0.s
+++ b/contiki-cpc/arch/crt0.s
@@ -18,7 +18,7 @@
 	call	_main
 
 _exit::
-	ret
+	rst #0
 
 	.area _HOME
 	.area _CODE
diff --git a/contiki-cpc/conf/program-handler-conf.h b/contiki-cpc/conf/program-handler-conf.h
index 26a7dc6..a721fdf 100644
--- a/contiki-cpc/conf/program-handler-conf.h
+++ b/contiki-cpc/conf/program-handler-conf.h
@@ -36,5 +36,9 @@
 #define __PROGRAM_HANDLER_CONF_H__
 
 #define PROGRAM_HANDLER_CONF_MAX_NUMDSCS 10
+#define PROGRAM_HANDLER_CONF_QUIT_MENU   1
+
+#define EXIT_SUCCESS 0
+void exit(int);
 
 #endif /* __PROGRAM_HANDLER_CONF_H__ */