CWallet class

* A new class CKeyStore manages private keys, and script.cpp depends on access to CKeyStore.
* A new class CWallet extends CKeyStore, and contains all former wallet-specific globals; CWallet depends on script.cpp, not the other way around.
* Wallet-specific functions in CTransaction/CTxIn/CTxOut (GetDebit, GetCredit, GetChange, IsMine, IsFromMe), are moved to CWallet, taking their former 'this' argument as an explicit parameter
* CWalletTx objects know which CWallet they belong to, for convenience, so they have their own direct (and caching) GetDebit/... functions.
* Some code was moved from CWalletDB to CWallet, such as handling of reserve keys.
* Main.cpp keeps a set of all 'registered' wallets, which should be informed about updates to the block chain, and does not have any notion about any 'main' wallet. Function in main.cpp that require a wallet (such as GenerateCoins), take an explicit CWallet* argument.
* The actual CWallet instance used by the application is defined in init.cpp as "CWallet* pwalletMain". rpc.cpp and ui.cpp use this variable.
* Functions in main.cpp and db.cpp that are not used by other modules are marked static.
* The code for handling the 'submitorder' message is removed, as it not really compatible with the idea that a node is independent from the wallet(s) connected to it, and obsolete anyway.

src/keystore.h

@@ -4,7 +4,23 @@
 #ifndef BITCOIN_KEYSTORE_H
 #define BITCOIN_KEYSTORE_H
 
-bool AddKey(const CKey& key);
-std::vector<unsigned char> GenerateNewKey();
+class CKeyStore
+{
+public:
+    std::map<std::vector<unsigned char>, CPrivKey> mapKeys;
+    mutable CCriticalSection cs_mapKeys;
+    virtual bool AddKey(const CKey& key);
+    bool HaveKey(const std::vector<unsigned char> &vchPubKey) const
+    {
+        return (mapKeys.count(vchPubKey) > 0);
+    }
+    CPrivKey GetPrivKey(const std::vector<unsigned char> &vchPubKey) const
+    {
+        std::map<std::vector<unsigned char>, CPrivKey>::const_iterator mi = mapKeys.find(vchPubKey);
+        if (mi != mapKeys.end())
+            return (*mi).second;
+    }
+    std::vector<unsigned char> GenerateNewKey();
+};
 
 #endif