Set default minrelaytxfee to 1000 zatoshis to match upstream.

A txout will be considered dust when it has a value <546 zatoshis.
Helps to address #1719.

src/main.h

@@ -60,6 +60,8 @@ static const int ALERT_PRIORITY_SAFE_MODE = 4000;
 static const unsigned int MAX_P2SH_SIGOPS = 15;
 /** The maximum number of sigops we're willing to relay/mine in a single tx */
 static const unsigned int MAX_STANDARD_TX_SIGOPS = MAX_BLOCK_SIGOPS/5;
+/** Default for -minrelaytxfee, minimum relay fee for transactions */
+static const unsigned int DEFAULT_MIN_RELAY_TX_FEE = 1000;
 /** Default for -maxorphantx, maximum number of orphan transactions kept in memory */
 static const unsigned int DEFAULT_MAX_ORPHAN_TRANSACTIONS = 100;
 /** The maximum size of a blk?????.dat file (since 0.8) */