use rtt for ack timeout

Garlic.h

@@ -44,6 +44,7 @@ namespace garlic
 	const int OUTGOING_TAGS_CONFIRMATION_TIMEOUT = 10; // 10 seconds 
 	const int LEASET_CONFIRMATION_TIMEOUT = 4000; // in milliseconds
 	const int ROUTING_PATH_EXPIRATION_TIMEOUT = 30; // 30 seconds 
+	const int ROUTING_PATH_MAX_NUM_TIMES_USED = 10; // how many times might be used 
 	
 	struct SessionTag: public i2p::data::Tag<32> 
 	{
@@ -64,6 +65,7 @@ namespace garlic
 		std::shared_ptr<const i2p::data::Lease> remoteLease;
 		int rtt; // RTT
 		uint32_t updateTime; // seconds since epoch
+		int numTimesUsed; 
 	};	
 	
 	class GarlicDestination;