Move FORMAT parsing into send code.

adsbus/opts.h

@@ -2,8 +2,6 @@
 
 #include <stdbool.h>
 
-struct flow;
-
 typedef bool (*opts_handler)(const char *);
 typedef char opts_group[1];
 
@@ -11,4 +9,3 @@ void opts_init(int, char *[]);
 void opts_add(const char *, const char *, opts_handler, opts_group);
 void opts_call(opts_group);
 char *opts_split(const char **, char);
-bool opts_add_send(bool (*)(const char *, struct flow *, void *), struct flow *, const char *);