Switch from sketchy dup() juggling to callbacks to retry outgoing connection.

adsbus/send.h

@@ -1,11 +1,12 @@
 #pragma once
 
 struct packet;
+struct peer;
 
 void send_init();
 void send_cleanup();
 struct serializer *send_get_serializer(char *);
-void send_add(int, struct serializer *);
-void send_add_wrapper(int, void *);
+void send_new(int, struct serializer *, struct peer *);
+void send_new_wrapper(int, void *, struct peer *);
 void send_write(struct packet *);
 void send_print_usage();