Move all SQL operations on ledger close into the ledger code so we can

accept ledgers without having to participate in the consensus process. We'll
need this when we implement "catch up".

Move AcctTx into the same connection as Txn so they can be part of a single
transaction.

Dispatch ledger accept synchronization functions into a detached thread so it
doesn't stall our I/O engine.

src/SerializedTransaction.h

@@ -10,6 +10,11 @@
 #include "TransactionFormats.h"
 #include "NewcoinAddress.h"
 
+#define TXN_SQL_NEW			'N'
+#define TXN_SQL_CONFLICT	'C'
+#define TXN_SQL_HELD		'H'
+#define TXN_SQL_VALIDATED	'V'
+
 class SerializedTransaction : public SerializedType
 {
 public: