Remove switch case fallthrough

[Paul Backus]

On Friday, 21 May 2021 at 19:25:22 UTC, Ogi wrote:
> On Friday, 14 May 2021 at 20:58:57 UTC, Dennis wrote:
>> ```D
>> void main() {
>>     int x = 3;
>>     string name = x switch {
>>         0 => "zero",
>>         1 => "one",
>>         2 => "two",
>>     };
>> }
>> ```
>
> This particular example can be emulated with this template:
>
> ```D
> template mapSwitch(alias map)
> {
> ```

There's also [`std.algorithm.comparison.predSwitch`][1] in 
Phobos, which does something similar.

[1]: 
http://phobos.dpldocs.info/std.algorithm.comparison.predSwitch.html