rename "closure-ref" to "free-ref"; s/vars/variables/ in some names

* libguile/programs.h:
* libguile/programs.c: (SCM_PROGRAM_FREE_VARIABLES): Rename from
  SCM_PROGRAM_FREE_VARS. Callers changed.
* libguile/programs.c (scm_make_program): Rename arg to
  "free_variables".
  (scm_program_free_variables): Rename from program-free-vars.

* libguile/vm-engine.h:
* libguile/vm-engine.c (VM_CHECK_FREE_VARIABLES): Rename from
  VM_CHECK_CLOSURE.
  (vm_engine, CACHE_PROGRAM): Rename closure and closure_count to free_vars and
  free_vars_vount.

* libguile/vm-i-system.c (FREE_VARIABLE_REF): Rename from CLOSURE_REF.
  (free-ref, free-boxed-ref, free-boxed-set): Rename from closure-ref,
  closure-boxed-ref, closure-boxed-set.
  (make-closure): Renamed from make-closure2.

* module/language/glil/compile-assembly.scm (glil->assembly): Hack to
  never write out the the old "make-closure" instruction. Will fix
  better later. Change to emit free-ref etc instead of closure-ref.

* module/language/tree-il/compile-glil.scm (flatten): Emit make-closure
  instead of make-closure2, now that the old make-closure is gone.

* module/system/vm/program.scm (system): Rename program-free-vars to
  program-free-variables.

* test-suite/tests/tree-il.test ("lambda"): Update for make-closure.

module/language/glil/compile-assembly.scm

@@ -178,7 +178,7 @@
              (emit-code (align-program prog addr)))
             (else
              (let ((table (dump-object (make-object-table objects) addr))
-                   (closure (if (> closure-level 0) '((make-closure)) '())))
+                   (closure  '()))
                (cond
                 (object-alist
                  ;; if we are being compiled from something with an object
@@ -267,8 +267,8 @@
                 ((empty-box) 'empty-box)
                 (else (error "what" op)))
               (case op
-                ((ref) (if boxed? 'closure-boxed-ref 'closure-ref))
-                ((set) (if boxed? 'closure-boxed-set (error "what." glil)))
+                ((ref) (if boxed? 'free-boxed-ref 'free-ref))
+                ((set) (if boxed? 'free-boxed-set (error "what." glil)))
                 (else (error "what" op))))
          ,index))))
     

module/language/tree-il/compile-glil.scm

@@ -503,7 +503,7 @@
                        (else (error "what" x loc))))
                    free-locs)
                   (emit-code #f (make-glil-call 'vector (length free-locs)))
-                  (emit-code #f (make-glil-call 'make-closure2 2))))
+                  (emit-code #f (make-glil-call 'make-closure 2))))
             (if (eq? context 'tail)
                 (emit-code #f (make-glil-call 'return 1)))))))
       

module/system/vm/program.scm

@@ -33,7 +33,7 @@
            
             program-arity program-meta
             program-objcode program? program-objects
-            program-module program-base program-free-vars))
+            program-module program-base program-free-variables))
 
 (load-extension "libguile" "scm_init_programs")