Remove switch case fallthrough

[Mathias LANG]

On Thursday, 13 May 2021 at 16:56:58 UTC, Adam D. Ruppe wrote:
> On Thursday, 13 May 2021 at 16:51:07 UTC, Imperatorn wrote:
>> Please don't add *more* to the language. Just remove 
>> fallthrough. Done.
>
> Or better yet just leave it alone (existing deprecation to 
> error is ok though). The explicit status quo is a solid 
> situation.

Exactly this. The error should not go away, because it would be a 
major silent difference when porting code from C. And common, 
adding `break` doesn't have any kind of objective downside.