Use Tree-IL-like case-lambda clause chaining in CPS

Use Tree-IL-like case-lambda clause chaining in CPS

* module/language/cps.scm ($kclause, $kentry): Instead of having an
  entry continuation contain a list of clauses, have the clauses contain
  clauses (as in Tree-IL).  In some ways it's not as convenient but it
  does reflect the continuation tree correctly.

* module/language/cps/arities.scm:
* module/language/cps/closure-conversion.scm:
* module/language/cps/compile-bytecode.scm:
* module/language/cps/constructors.scm:
* module/language/cps/contification.scm:
* module/language/cps/dce.scm:
* module/language/cps/dfg.scm:
* module/language/cps/elide-values.scm:
* module/language/cps/prune-top-level-scopes.scm:
* module/language/cps/reify-primitives.scm:
* module/language/cps/renumber.scm:
* module/language/cps/simplify.scm:
* module/language/cps/slot-allocation.scm:
* module/language/cps/specialize-primcalls.scm:
* module/language/cps/verify.scm:
* module/language/tree-il/compile-cps.scm: Adapt aaaaaaall users.