[Issue 23680] Support static classes in D

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23680

--- Comment #2 from Marcelo Silva Nascimento Mancini <msnmancini at hotmail.com> ---
Yea I'm aware but this is really not intuitive for beginners. Plus, there's no
way to do that using a single file. Like, it's not really me, but
People.Like.Doing.That.Way, always uppercase, specially from people coming from
Java which they directly imported a class.

Yea `static class` has no meaning for top level, so, for me, the solution to
that is giving it a meaning by or implementing the static class functionality
from other languages or giving it an error.

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