[Wallet] extend CKeyMetadata with HD keypath

Zcash: modified for zip32

src/wallet/walletdb.h

@@ -77,9 +77,13 @@ public:
 class CKeyMetadata
 {
 public:
-    static const int CURRENT_VERSION=1;
+    static const int VERSION_BASIC=1;
+    static const int VERSION_WITH_HDDATA=10;
+    static const int CURRENT_VERSION=VERSION_WITH_HDDATA;
     int nVersion;
     int64_t nCreateTime; // 0 means unknown
+    std::string hdKeypath; //optional HD/zip32 keypath
+    uint256 seedFp;
 
     CKeyMetadata()
     {
@@ -89,6 +93,7 @@ public:
     {
         nVersion = CKeyMetadata::CURRENT_VERSION;
         nCreateTime = nCreateTime_;
+        hdKeypath.clear();
     }
 
     ADD_SERIALIZE_METHODS;
@@ -97,12 +102,18 @@ public:
     inline void SerializationOp(Stream& s, Operation ser_action) {
         READWRITE(this->nVersion);
         READWRITE(nCreateTime);
+        if (this->nVersion >= VERSION_WITH_HDDATA)
+        {
+            READWRITE(hdKeypath);
+            READWRITE(seedFp);
+        }
     }
 
     void SetNull()
     {
         nVersion = CKeyMetadata::CURRENT_VERSION;
         nCreateTime = 0;
+        hdKeypath.clear();
     }
 };