Tx queue enhancements and RPC info (RIPD-1205, RIPD-1206):

* Account-related queue stats (RIPD-1205). Boolean "queue" parameter to
  account_info only if requesting the open ledger.
* Account for the TxQ when autofilling sequence in sign-and-submit (RIPD-1206)
* Tweak TxQ::accept edge case when choosing which tx to try next.
* Labels for experimental "x_" submit parameters use correct separator.

=== Release Notes ===
==== New features ====

When requesting `account_info` for the open ledger, include the `queue :
true` to get extra information about any queued transactions for this
account. (RIPD-1205).

==== Bug fixes ====

When using sign-and-submit mode to autofill a transaction's sequence
number, the logic will not reuse a sequence number that is in the queue
for this account. (RIPD-1206).

Labels for experimental "x_queue_okay" and "x_assume_tx" parameters to
`sign` and `submit` updated to use correct separator.

src/ripple/app/misc/NetworkOPs.cpp

@@ -1409,7 +1409,7 @@ void NetworkOPsImp::switchLastClosedLedger (
 
     // Update fee computations.
     // TODO: Needs an open ledger
-    //app_.getTxQ().processValidatedLedger(app_, *newLCL, true);
+    //app_.getTxQ().processClosedLedger(app_, *newLCL, true);
 
     // Caller must own master lock
     {