110.01.00

- Changed `Queue` from a linked to an array-backed implementation.

  Renamed the previous implementation to `Linked_queue`.

  Renamed `transfer`, which was constant time, as `blit_transfer`,
  which is linear time.

  Removed `partial_iter`.  One can use `with_return`.

  Added `singleton`, `filter`, `get`, `set`.
- For `Error` and `Info`, changed `to_string_hum` to use `sexp_of_t`
  and `Sexp.to_string_hum`, rather than a custom string format.
- Changed the output format of `Validate.errors` to be a sexp.
- Added `Hashtbl.of_alist_or_error` and `Map.of_alist_or_error`.
- Added `String_id.Make` functor, which includes a module name for
  better error messages.
- Exposed `Bucket.size`.
- Changed the default for `Debug.should_print_backtrace` to be `false`
  rather than `true`.

  Usually the backtraces are noise.
- Removed the tuning of gc parameters built in to Core, so that the
  default is now the stock OCaml settings.

  Such tuning doesn't belong in Core, but rather done per application.
  Also, the Core settings had fallen way out of date, and not kept up
  with changes in the OCaml runtime settings.  We have one example
  (lwt on async) where the Core settings significantly slowed down a
  program.
- Added `Exn.raise_without_backtrace`, to raise without building a
  backtrace.

  `raise_without_backtrace` never builds a backtrace, even when
  `Backtrace.am_recording ()`.
- Made `with_return` faster by using `Exn.raise_without_backtrace`.
- Improved `with_return` to detect usage of a `return` after its
  creating `with_return` has returned.