1.0.9.46: take pv-slot value from wrapper-slot-table

1.0.9.46: take pv-slot value from wrapper-slot-table

* Use NIL instead of T in the CAR of the SLOT-TABLE cells to indicate
  "slot location not saved for some reason".

* Better slot location computation for SLOT-TABLES: remaining wrapper
  copies now also copy the slot-table, and bootstrapping computes the
  slot locations for rest of the interesting cases.

* Use SLOT-TABLE to obtain the slot location for permutation vectors
  instead of WRAPPER-CLASS-SLOTS and WRAPPER-INSTANCE-SLOTS-LAYOUT.
  Faster, and slowly point the way to getting rid of WRAPPER/LAYOUT
  distinction.

* We deal with slot names in permutation vectors: remove the unused
  code that computed things for non-slot-name places in them.