Simplification of @trusted

[Sönke Ludwig]

Am 16.06.2021 um 13:38 schrieb RazvanN:
> Currently, @trusted applies only to functions. This is most of the times 
> a pain when you want trusted code blocks inside functions. Why not 
> simplify it a bit by using trusted scope blocks?

Yes, please! There are 800 of these in vibe.d alone. There has also been 
an issue where the delegate workaround was erroneously flagged as a heap 
delegate, causing considerable GC memory load.

`@trusted` *should* probably not even be available for functions (of 
course it is not a desirable breaking change to disallow that now, though).