gettransaction RPC for non-wallet transactions

Works for wallet transactions, memory-pool transaction and block chain
transactions.

Available for all:
 * txid
 * version
 * locktime
 * size
 * coinbase/inputs/outputs
 * confirmations

Available only for wallet transactions:
 * amount
 * fee
 * details
 * blockindex

Available for wallet transactions and block chain transactions:
 * blockhash
 * time

src/main.cpp

@@ -733,7 +733,31 @@ int CTxIndex::GetDepthInMainChain() const
     return 1 + nBestHeight - pindex->nHeight;
 }
 
-
+// Return transaction in tx, and if it was found inside a block, its hash is placed in hashBlock
+bool GetTransaction(const uint256 &hash, CTransaction &tx, uint256 &hashBlock)
+{
+    {
+        LOCK(cs_main);
+        {
+            LOCK(mempool.cs);
+            if (mempool.exists(hash))
+            {
+                tx = mempool.lookup(hash);
+                return true;
+            }
+        }
+        CTxDB txdb("r");
+        CTxIndex txindex;
+        if (tx.ReadFromDisk(txdb, COutPoint(hash, 0), txindex))
+        {
+            CBlock block;
+            if (block.ReadFromDisk(txindex.pos.nFile, txindex.pos.nBlockPos, false))
+                hashBlock = block.GetHash();
+            return true;
+        }
+    }
+    return false;
+}