Fix getbalance discrepency

Two changes:

Use IsConfirmed() instead of IsFinal(), so 'getbalance "*" 0' uses the same
'is this output spendable' criteria as 'getbalance'. Fixes issue #172.

And a tiny refactor to CWallet::GetBalance() (redundant call to IsFinal -- IsConfirmed
calls IsFinal).
getbalance with no arguments and 'getbalance "*" 0' could return different different results,

src/rpcwallet.cpp

@@ -519,12 +519,12 @@ Value getbalance(const Array& params, bool fHelp)
     if (params[0].get_str() == "*") {
         // Calculate total balance a different way from GetBalance()
         // (GetBalance() sums up all unspent TxOuts)
-        // getbalance and getbalance '*' should always return the same number.
+        // getbalance and getbalance '*' 0 should return the same number
         int64 nBalance = 0;
         for (map<uint256, CWalletTx>::iterator it = pwalletMain->mapWallet.begin(); it != pwalletMain->mapWallet.end(); ++it)
         {
             const CWalletTx& wtx = (*it).second;
-            if (!wtx.IsFinal())
+            if (!wtx.IsConfirmed())
                 continue;
 
             int64 allFee;

src/wallet.cpp

@@ -899,7 +899,7 @@ int64 CWallet::GetBalance() const
         for (map<uint256, CWalletTx>::const_iterator it = mapWallet.begin(); it != mapWallet.end(); ++it)
         {
             const CWalletTx* pcoin = &(*it).second;
-            if (pcoin->IsFinal() && pcoin->IsConfirmed())
+            if (pcoin->IsConfirmed())
                 nTotal += pcoin->GetAvailableCredit();
         }
     }