Add a default net port parameter to each network.

ok @jrick

params.go

@@ -50,6 +50,7 @@ type Checkpoint struct {
 type Params struct {
 	Name        string
 	Net         btcwire.BitcoinNet
+	DefaultPort string
 
 	// Chain parameters
 	GenesisBlock           *btcwire.MsgBlock
@@ -85,6 +86,7 @@ type Params struct {
 var MainNetParams = Params{
 	Name:        "mainnet",
 	Net:         btcwire.MainNet,
+	DefaultPort: "8333",
 
 	// Chain parameters
 	GenesisBlock:           &genesisBlock,
@@ -140,6 +142,7 @@ var MainNetParams = Params{
 var RegressionNetParams = Params{
 	Name:        "regtest",
 	Net:         btcwire.TestNet,
+	DefaultPort: "18444",
 
 	// Chain parameters
 	GenesisBlock:           &regTestGenesisBlock,
@@ -180,6 +183,7 @@ var RegressionNetParams = Params{
 var TestNet3Params = Params{
 	Name:        "testnet3",
 	Net:         btcwire.TestNet3,
+	DefaultPort: "18333",
 
 	// Chain parameters
 	GenesisBlock:           &testNet3GenesisBlock,