112.06.00

- Sped up `float` and `float array` operations.
- Removed a use of `Obj.magic` in code generated by `pa_bin_prot` for
  polymorphic variants that led to memory unsafety.

    Previously, `pa_bin_prot` generated this kind of code for
    polymorphic variants:

        match Obj.magic (read_int buf pos) with
        | `A as x -> x
        | `B as x -> x
        | `C -> `C (read_float buf pos)
        | _ -> fail

    and this caused the compiler to assume the result is an immediate
    value.  To fix this we removed the `as x -> x` and used the computed
    integer hash.