Access base_uint through public members (RIPD-898):

* Updates many (but probably not all) locations that access base_uint
  private storage.
* More calls to access base_uint through members.
* Use an iterator to write Serializer collections.

src/ripple/protocol/impl/AccountID.cpp

@@ -147,7 +147,7 @@ calcAccountID (PublicKey const& pk)
     auto const d = static_cast<
         ripesha_hasher::result_type>(rsh);
     AccountID id;
-    static_assert(sizeof(d) == sizeof(id), "");
+    static_assert(sizeof(d) == id.size(), "");
     std::memcpy(id.data(), d.data(), d.size());
     return id;
 }