Changed the output as being a function returning the functor.

Instead of creating a nullary procedure that stores the defined
functor in the boot virtual fs, no we create a unary procedure
that stores the functor in its first argument. Put differently,
it is a function returning the functor.
Reconciled the pickle and boot-pickle formats.
Output the abstraction instead of its codearea.
Do not bind <Base>.'Base' = <Base> anymore.
Fixed: lazy funs did not return a read-only.