fix LP inter-mixing by not initiating new queues by them

Closes: #623

src/darksend.cpp

@@ -1569,6 +1569,9 @@ bool CDarksendPool::DoAutomaticDenominating(bool fDryRun)
             }
         }
 
+        // do not initiate queue if we are a liquidity proveder to avoid useless inter-mixing
+        if(nLiquidityProvider) return false;
+
         int i = 0;
 
         // otherwise, try one randomly