Quick fix for the bug that was causing ledgers to diverge.

LES used an unordered map, causing the traverse of modified ledger nodes to
be in random order. This meant different nodes would thread transactions
differently, causing ledger divergence. This change switches the LES code to
use a standard map. This adds more overhead to LES search functions (because
ordered map operations like search and insert are more expensive than
unordered map opreations, so it may be worth a separate ordering step just
for calcRawMeta instead.

src/TransactionEngine.cpp

@@ -18,7 +18,7 @@ SETUP_LOG();
 void TransactionEngine::txnWrite()
 {
 	// Write back the account states
-	for (boost::unordered_map<uint256, LedgerEntrySetEntry>::iterator it = mNodes.begin(), end = mNodes.end();
+	for (std::map<uint256, LedgerEntrySetEntry>::iterator it = mNodes.begin(), end = mNodes.end();
 			it != end; ++it)
 	{
 		const SLE::pointer&	sleEntry	= it->second.mEntry;