Change fee escalation algorithms (RIPD-1177):

* Minimum factor 256*500, don't multiply by base fee
* Change autofill fee behavior to pay the open ledger fee.
** Experimental options: x-assume-tx - assume <int> more transactions in
   the open queue when computing escalated fee, x-queue-okay - if true
   and escalated fee is over limit, try with load fee.
* Port of 75af4ed.

src/ripple/rpc/handlers/Submit.cpp

@@ -55,7 +55,6 @@ Json::Value doSubmit (RPC::Context& context)
         context.role,
         context.ledgerMaster.getValidatedLedgerAge(),
         context.app,
-        context.ledgerMaster.getCurrentLedger(),
         RPC::getProcessTxnFn (context.netOps));
     }