* libguile/vm-engine.c (prompt): Adapt to explicitly set the saved SP so
we know how many incoming values the handler will receive, and to make
escape-only? a flag.
* module/language/cps/compile-rtl.scm (emit-rtl-sequence): $prompt
should only be found in a "seq" context, as it just pushes on a prompt
and doesn't bind any values. On the other hand it should emit
appropriate code for the handler to bind its values, so do that.
* module/language/cps/slot-allocation.scm ($cont-allocation): Add a note
that proc-slot is used by prompts as well.
(allocate-slots): Compute the allocation of a prompt handler's args.
* module/language/tree-il/compile-cps.scm (convert): Use "unwind"
instead of the nonexistent "pop-prompt".
* module/system/vm/disassembler.scm (code-annotation): Adapt to change
in prompt VM op.
* module/language/tree-il/compile-cps.scm: New module implementing CPS
conversion of Tree-IL.
* module/Makefile.am:
* module/language/tree-il/spec.scm:
* module/language/cps/spec.scm: Integrate CPS in the build and language
system.
