Sync connect() + async loop_start() works best, despite the guides

(Stress tests obviously needed.)

ipaacalib/cpp/include/ipaaca/ipaaca-participants.h

@@ -300,8 +300,8 @@ class MQTTParticipant: public ParticipantCore, public mosqpp::mosquittopp {
             IPAACA_DEBUG("Created MQTTParticipant on " << host << ":" << port << " for scope " << _scope << " with prepared client id " << _client_id)
         };
         IPAACA_HEADER_EXPORT inline void run_in_background() {
+            int res = connect(host.c_str(), port, keepalive);
             loop_start();
-            int res = connect_async(host.c_str(), port, keepalive);
             if (res!=0) {
                 IPAACA_ERROR("connect_async (on topic " << _scope << ") returned an error " << res)
             } else {