[Aggregator] Fix autocalibration hello thread

- A second instance of monitor_couples() was threaded instead of
  listen_for_aps() (copy/paste fail!).
- Fix a typo in the config variable "autocalbration_port".
- Add some debug messages.

infrastructure-centred/owlps-aggregator/owlps-aggregatord.c

@@ -50,7 +50,7 @@ int main(int argc, char **argv)
   pthread_create(&monitor_thread, NULL,
                  (void *) &monitor_couples, NULL) ;
   pthread_create(&autocalibration_hello_thread, NULL,
-                 (void *) &monitor_couples, NULL) ;
+                 (void *) &listen_for_aps, NULL) ;
 
   run = TRUE ;
   ret = read_loop(sockfd) ;
@@ -103,7 +103,7 @@ void parse_config_file(int argc, char **argv)
       // Autocalibration activated?
       CFG_BOOL("autocalibration", cfg_false, CFGF_NONE),
       // Port on which autocalibration data are exchanged:
-      CFG_INT("autocalbration_port", DEFAULT_AUTOCALIBRATION_PORT,
+      CFG_INT("autocalibration_port", DEFAULT_AUTOCALIBRATION_PORT,
               CFGF_NONE),
       // Time we keep APs in the list (in seconds):
       CFG_INT("ap_keep_timeout", DEFAULT_AP_KEEP_TIMEOUT, CFGF_NONE),
@@ -377,6 +377,10 @@ void* monitor_couples()
   couple_info info;
   int sockfd;
 
+#ifdef DEBUG
+  fprintf(stderr, "Monitor couples thread launched.\n") ;
+#endif // DEBUG
+
   sockfd = create_udp_sending_socket(cfg_getstr(cfg, "positioner_ip"),
                                      cfg_getint(cfg, "positioner_port"),
                                      &serv, &client) ;
@@ -663,6 +667,10 @@ void listen_for_aps(void)
   socklen_t client_len = sizeof(client) ; // Size of clients
   autocalibration_hello message ;
 
+#ifdef DEBUG
+  fprintf(stderr, "Autocalibration Hello thread launched.\n") ;
+#endif // DEBUG
+
   listen_sockfd =
     create_udp_listening_socket(cfg_getint(cfg,
                                            "autocalibration_port")) ;
@@ -684,6 +692,10 @@ void listen_for_aps(void)
             fprintf(stderr, "No message received from aggregator!\n") ;
           continue ;
         }
+#ifdef DEBUG
+      else
+        fprintf(stderr, "Got a Hello message.\n") ;
+#endif // DEBUG
 
       update_ap(message.ap_mac_addr_bytes, message.ap_ip_addr) ;
     }