This replaces the experimental validators module with foundational
code to implement a new system for tracking validators, validations and
the UNL. The code is turned off by default, in BeastConfig.h
* Remove obsolete public Manager interfaces
* Remove obsolete database methods
* Remove obsolete ChosenList concept
* Remove obsolete code
* Add missing includes
* Tidy up STValidation.h
* Move factory function to Validators::make_Manager
* Add Connection object for tracking STValidations
* New ripple container aliases use hardened_hash
* Use std::tuple instead of boost::tuple
* Use std unordered containers instead of boost
* Fix Destroyer for new containers
* Fix warning for fnv1a on 32-bit arch
* Validator fixes for new containers