'sortloot' revamp

'sortloot' revamp

Change the sortloot option to use qsort() instead of naive insertion
sort.  After sorting, it reorders the linked list into the sorted
order, so might have some subtle change(s) in behavior since that
wasn't done before.

pickup.c includes some formatting cleanup.

modified:
  include/extern.h, hack.h, obj.h
  src/do.c, do_wear.c, end.c, invent.c, pickup.c