Adding Dandelion++ support to public networks:

- New flag in NOTIFY_NEW_TRANSACTION to indicate stem mode
  - Stem loops detected in tx_pool.cpp
  - Embargo timeout for a blackhole attack during stem phase

src/cryptonote_protocol/levin_notify.h

@@ -35,6 +35,7 @@
 
 #include "byte_slice.h"
 #include "cryptonote_basic/blobdatatype.h"
+#include "cryptonote_protocol/enums.h"
 #include "cryptonote_protocol/fwd.h"
 #include "net/enums.h"
 #include "span.h"
@@ -122,7 +123,7 @@ namespace levin
           particular stem.
 
       \return True iff the notification is queued for sending. */
-    bool send_txs(std::vector<blobdata> txs, const boost::uuids::uuid& source);
+    bool send_txs(std::vector<blobdata> txs, const boost::uuids::uuid& source, i_core_events& core, relay_method tx_relay);
   };
 } // levin
 } // net