Make Base.checked_add and friends public

[LilithHafner]

No description provided.

[LilithHafner]

According to the literal definition of the Julia API, it would not be breaking to change Base's using Checked to import Checked which would not break the public Base.Checked or the public Base.Checked.checked_add. I'd like to extend the API to guarantee that Base will continue to define the symbol checked_add directly (e.g. via using Checked or using Checked: checked_add).

Automated tools (e.g. the REPL) will use the literal definition so we should make sure it's accurate. For example:

help?> Base.checked_add
  │ Warning
  │
  │  The following bindings may be internal; they may change or be
  │  removed in future versions:
  │
  │    •  Base.checked_add

  Base.checked_add(x, y)

  Calculates x+y, checking for overflow errors where applicable.

  The overflow protection may impose a perceptible performance penalty.

We should do this with all symbols exported into Base that are intended to be publicly accessible with Base.symbol.

[LilithHafner]

In that case, the docstring of checked_add should be changed to not use Base.checked_add.

[Priynsh]

In that case, the docstring of checked_add should be changed to not use Base.checked_add.

should the docstrings of other functions like checked_sub, checked_mul, etc also be changed?

[nsajko]

Actually, I agree with Lilith. I think it'd be better to keep the doc strings as-is, considering they've been this way for quite a long time, and just make the bindings public in Base.