Initial implementation of statuses using objects in place of nested records.

Initial implementation of statuses using objects in place of nested records.
So nicer!

The only major problem is that the NCicLibrary functor does not return a
function #status as 'status -> 'status, but a function status -> status.
Thus I have to painfully wrap NCicLibrary.Realizer(...).require in NRstatus.

TO REMEMBER:
- every function that works on a data type that used to be put in the status
  (e.g. a db) must now work on a functional class with just two members
  (db and set_db). Moreover, every function in the module must work on the
  open variants of the class type, i.e. #status