Eliminate BKPT macro in favor of procedure. The macro used

Eliminate BKPT macro in favor of procedure.  The macro used
(THE-ENVIRONMENT), which screwed the compiler.  The procedure uses the
environment of the first subproblem of the continuation of the call,
which in many cases is the same thing.

The effect of the old BKPT macro can still be achieved by writing

(breakpoint-procedure (the-environment) ...)