Type and range inference for CPS

* module/language/cps/types.scm: New file, implementing type and range
  inference over CPS.

* module/language/cps/type-fold.scm: New file, implementing abstract
  constant folding for CPS.

* module/Makefile.am: Add the new files.

* module/language/cps/compile-bytecode.scm: Wire up type-fold, but
  currently disabled.
Enable type folding

* module/language/cps/compile-bytecode.scm (optimize): Enable type
  folding.
Compile language/cps/types.scm early

* module/Makefile.am (BOOT_SOURCES, BOOT_GOBJECTS): New variables.
  (CLEANFILES, nobase_mod_DATA, nobase_ccache_DATA, EXTRA_DIST)
  (ETAGS_ARGS): Use the new variables.

  (CPS_LANG_SOURCES): Remove language/cps/types.scm, as it is a boot
  file.
Limit impact of O(n^2) type analysis by imposing limit

* module/language/cps/types.scm (infer-types): Add #:max-label-count
  argument.

* module/language/cps/type-fold.scm (compute-folded, fold-constants*):
  Disable for big functions.  Perhaps we can relax this if we find an
  O(n log n) way to represent types.
DCE uses type analysis to elide type checks

* module/language/cps/dce.scm (elide-type-checks!, compute-live-code):
  Replace old ad-hoc type check elision with one driven from type
  analysis.  Type check elision only operates on smallish functions, to
  avoid n**2 explosion in type inference.
Redefine memory kind part of effects to be enumeration, not flags

* module/language/cps/effects-analysis.scm (define-enumeration): New
  helper.
  (&memory-kind-mask): Define as an enumeration, not a bitfield.  Add
  &unknown-memory-kinds.
  (&all-effects, effect-clobbers?, make-prompt-tag, expression-effects):
  Adapt.

Note that this change requires dce.go and cse.go to be recompiled.
Update effects-analysis docstring.

* module/language/cps/effects-analysis.scm: Update docs.