std.string import cleanup: how to fix regression?

[Ilya Yaroshenko via Digitalmars-d]

One solution is new `extern import std.array : split;` syntax. 
Like `public` but do *not* visible for module itself.
If user will use selective imports with std.string, than there 
compiler can deduce dependencies without full imports.

Furthermore we can deprecate it lately with  `deprecated extern 
import std.array : split;`

> What should we do? Anybody has a good idea for getting rid of 
> the
> gratuitous dependency on std.algorithm / std.array without 
> breaking user
> code with no warning?
>
>
> T