Support sending to script (P2SH) addresses

Upstream partials from 9e470585b3, e679ec969c, and 922e8e2929.

src/base58.h

@@ -242,6 +242,14 @@ public:
 class CBitcoinAddress : public CBase58Data
 {
 public:
+    enum
+    {
+        PUBKEY_ADDRESS = 0,
+        SCRIPT_ADDRESS = 5,
+        PUBKEY_ADDRESS_TEST = 111,
+        SCRIPT_ADDRESS_TEST = 196,
+    };
+
     bool SetHash160(const uint160& hash160)
     {
         SetData(fTestNet ? 111 : 0, &hash160, 20);
@@ -260,9 +268,11 @@ public:
         switch(nVersion)
         {
             case 0:
+            case SCRIPT_ADDRESS:
                 break;
 
             case 111:
+            case SCRIPT_ADDRESS_TEST:
                 fExpectTestNet = true;
                 break;
 
@@ -271,6 +281,14 @@ public:
         }
         return fExpectTestNet == fTestNet && vchData.size() == nExpectedSize;
     }
+    bool IsScript() const
+    {
+        if (!IsValid())
+            return false;
+        if (fTestNet)
+            return nVersion == SCRIPT_ADDRESS_TEST;
+        return nVersion == SCRIPT_ADDRESS;
+    }
 
     CBitcoinAddress()
     {

src/script.h

@@ -654,7 +654,10 @@ public:
     void SetBitcoinAddress(const CBitcoinAddress& address)
     {
         this->clear();
-        *this << OP_DUP << OP_HASH160 << address.GetHash160() << OP_EQUALVERIFY << OP_CHECKSIG;
+        if (address.IsScript())
+            *this << OP_HASH160 << address.GetHash160() << OP_EQUAL;
+        else
+            *this << OP_DUP << OP_HASH160 << address.GetHash160() << OP_EQUALVERIFY << OP_CHECKSIG;
     }
 
     void SetBitcoinAddress(const std::vector<unsigned char>& vchPubKey)