(RFC) remove the Times trait in favour of `range`

It's not possible to break from `times` and it results in the
restrictions coming from closures. Using `for _ in range(0, n)` from the
start is simpler, rather than switching to it after hitting either of
these issues.

The `for` loop can be special-cased for `_` patterns as the old `for`
loop was, to avoid any increase in verbosity for the simplest cases.