Replace Journal public data members with member function accessors
in order to make Journal lighter weight. The change makes a
Journal cheaper to pass by value.
Also add missing stream checks (e.g., calls to JLOG) to avoid
text processing that ultimately will not be stored in the log.
Since a non-default STAccount is now guaranteed to always be
160 bits, it was possible to reduce the number of methods that
it provides.
In the process of narrowing the STAccount interface it became
reasonable to remove some methods that duplicated functionality.
A few classes offered both a value() and a getValue() method.
The getValue() method is removed from those classes.
* Remove ltCURRENT
* Change getOwnerInfo
* Use ReadView in TransactionSign
* Change AcceptedLedger and ProposedTransaction to use ReadView
* Change RPC::accounts
