[Issue 11811] Add "eval" to phobos

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=11811

--- Comment #3 from hsteoh at quickfur.ath.cx ---
Yeah, I think ctEval is a better name, otherwise people could misunderstand it
as runtime mixin, as it is used in other languages.

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