replace frame implementation with VM frames

replace frame implementation with VM frames

* libguile/stacks.h: Rework so that a stack doesn't copy information out
  of VM frames, it just holds onto a VM frame, along with the stack id
  and length. VM frames are now the only representation of frames in
  Guile.
  (scm_t_info_frame, SCM_FRAME_N_SLOTS, SCM_FRAME_REF, SCM_FRAME_NUMBER)
  (SCM_FRAME_FLAGS, SCM_FRAME_SOURCE, SCM_FRAME_PROC, SCM_FRAME_ARGS)
  (SCM_FRAME_PREV, SCM_FRAME_NEXT)
  (SCM_FRAMEF_VOID, SCM_FRAMEF_REAL, SCM_FRAMEF_PROC)
  (SCM_FRAMEF_EVAL_ARGS, SCM_FRAMEF_OVERFLOW)
  (SCM_FRAME_VOID_P, SCM_FRAME_REAL_P, SCM_FRAME_PROC_P)
  (SCM_FRAME_EVAL_ARGS_P, SCM_FRAME_OVERFLOW_P): Remove these macros
  corresponding to the old frame implementation.
  (scm_frame_p scm_frame_source, scm_frame_procedure)
  (scm_frame_arguments): These definitions are now in frames.h.
  (scm_last_stack_frame): Remove declaration of previously-removed
  constructor. Probably should re-instate it though.
  (scm_frame_number, scm_frame_previous, scm_frame_next)
  (scm_frame_real_p, scm_frame_procedure_p, scm_frame_evaluating_args_p)
  (scm_frame_overflow_p) : Remove these procedures corresponding to the
  old stack implementation.

* libguile/stacks.c: Update for new frames implementation.

* libguile/frames.h:
* libguile/frames.c: Rename functions operating on VM frames to have a
  scm_frame prefix, not scm_vm_frame -- because they really are the only
  frames we have. Rename corresponding Scheme functions too, from
  vm-frame-foo to frame-foo.

* libguile/deprecated.h: Remove scm_stack and scm_info_frame data types.

* libguile/vm.c (vm_dispatch_hook): Adapt to scm_c_make_frame name
  change.

* module/system/vm/frame.scm: No need to export functions provided
  frames.c now, as we load those procedures into the default environment
  now. Rename functions, and remove a couple of outdated, unused
  functions. The bottom half of this file is still bitrotten, though.

* libguile/backtrace.c: Rework to operate on the new frame
  representation. Also fix a bug displaying file names for compiled
  procedures.

* libguile/init.c: Load the VM much earlier, just because we can. Also
  it allows us to have frames.[ch] loaded in time for stacks to be
  initialized, so that scm_frame_arguments can do the right thing.