Part of #1969. Changing min fee calculation also changes the dust threshold.

src/primitives/transaction.h

@@ -274,7 +274,7 @@ public:
         // to spend something, then we consider it dust.
         // A typical txout is 34 bytes big, and will
         // need a CTxIn of at least 148 bytes to spend:
-        // so dust is a txout less than 546 satoshis 
+        // so dust is a txout less than 54 satoshis
         // with default minRelayTxFee.
         size_t nSize = GetSerializeSize(SER_DISK,0)+148u;
         return 3*minRelayTxFee.GetFee(nSize);