More fixes for book.mit.

Make DISPLAY-EXCEPTION call WRITE-CONDITION-REPORT to get more
information about conditions that are signalled.

Add defintions for WHEN, UNLESS, and LIST*.

Return a thunk from the MAKE-TOPLEVEL arg to INTERPRETER and SUITE-TEST,
rather than calling BIND-CONDITION-HANDLER, which was dropping into the
REPL before the RESUME continuation could be SET!.