Implement new amendment majority semantics :

This implements the tracking of when an amendment achieved a majority
in the ledger, ensuring that there's always network-wide agreement
on which amendments have achieved a majority and how long they've
held it.

* New fields
* Change transactor changes
* AmendmentTable API and implementation changes
* Update amendment enabled status on validated ledgers
* Reinstate support for ledger sequence in fee transactions

src/ripple/app/ledger/impl/LedgerMaster.cpp

@@ -27,6 +27,7 @@
 #include <ripple/app/ledger/impl/LedgerCleaner.h>
 #include <ripple/app/tx/apply.h>
 #include <ripple/app/main/Application.h>
+#include <ripple/app/misc/AmendmentTable.h>
 #include <ripple/app/misc/IHashRouter.h>
 #include <ripple/app/misc/NetworkOPs.h>
 #include <ripple/app/misc/CanonicalTXSet.h>
@@ -233,6 +234,7 @@ public:
         getApp().getOPs().updateLocalTx (l);
         getApp().getSHAMapStore().onLedgerClosed (getValidatedLedger());
         mLedgerHistory.validatedLedger (l);
+        getApp().getAmendmentTable().doValidatedLedger (l);
 
     #if RIPPLE_HOOK_VALIDATORS
         getApp().getValidators().onLedgerClosed (l->getLedgerSeq(),