Change block references in debug.log to full hash instead of just 0..20

src/main.h

@@ -176,7 +176,7 @@ CBlockIndex * InsertBlockIndex(uint256 hash);
 
 static inline std::string BlockHashStr(const uint256& hash)
 {
-    return hash.ToString().substr(0, 20);
+    return hash.ToString();
 }
 
 bool GetWalletFile(CWallet* pwallet, std::string &strWalletFileOut);