Framework for double-checking that transactions, as they will be applied,

don't break invariants.

src/cpp/ripple/TransactionCheck.cpp

@@ -0,0 +1,11 @@
+
+#include "TransactionErr.h"
+#include "TransactionEngine.h"
+
+// Double check a transaction's metadata to make sure no system invariants were broken
+// Call right before 'calcRawMeta'
+
+bool TransactionEngine::checkInvariants(TER result, const SerializedTransaction& txn, TransactionEngineParams params)
+{
+	return true;
+}