big reorg of scheme modules -- e.g. programs.c -> (system vm program)

big reorg of scheme modules -- e.g. programs.c -> (system vm program)

This reorganization kills the ugly module-export-all hacks in
bootstrap.scm and core.scm. In fact, it gets rid of core.scm entirely,
breaking out its functionality into separate files.

* module/system/vm/trace.scm:
* module/system/vm/profile.scm:
* module/system/vm/disasm.scm:
* module/system/vm/debug.scm:
* module/system/vm/conv.scm:
* module/system/vm/assemble.scm:
* module/system/repl/repl.scm:
* module/system/repl/common.scm:
* module/system/base/compile.scm:
* module/system/repl/command.scm: Update for changes, and fix a bug in
  procedure-documentation.

* module/system/vm/bootstrap.scm: Just call scm_bootstrap_vm, which
  handles setting load-compiled for us.

* module/system/vm/core.scm: Removed, functionality folded into other
  modules.

* module/system/vm/frame.scm: Export the C frame procedures here; also
  move scheme functions from core.scm here.

* module/system/vm/instruction.scm: New file, exports procedures from
  instructions.c.

* module/system/vm/objcode.scm: New file, exports procedures from
  objcodes.c.

* module/system/vm/program.scm: New file, exports procedures from
  programs.c, and some scheme functions originally from core.scm.

* module/system/vm/vm.scm: New file, from vm.c and core.scm.

* src/Makefile.am (libguile_vm_la_SOURCES): Add bootstrap.h.

* src/bootstrap.h: New file, prototypes scm_bootstrap_vm (), which the
  scm_init_* functions call.

* src/frames.h:
* src/frames.c (scm_init_frames):
* src/frames.c (scm_bootstrap_frames):

* src/vm.h:
* src/instructions.h:
* src/instructions.c (scm_init_instructions):
* src/instructions.c (scm_bootstrap_instructions):
* src/objcodes.h:
* src/objcodes.c (scm_bootstrap_objcodes):
* src/objcodes.c (scm_init_objcodes):
* src/programs.h:
* src/programs.c (scm_bootstrap_programs):
* src/programs.c (scm_init_programs):
* src/vm.c (scm_bootstrap_vm):
* src/vm.c (scm_init_vm): Call scm_bootstrap_vm() before doing anything
  in an init function. Bootstrap_vm will call bootstrap_instructions(),
  etc to initialize types, then set load-compiled to point to
  load-compiled/vm.

* src/vm.c (scm_load_compiled_with_vm): Code to load .go files, if
  they're present.