From the summary: "Renamed/Selective imports no longer create aliases for the introduced names."

------

This is a breaking change to make import mechanism usable and easily understandable. I think both selective and unselective (==basic) import should behave as same. Let's try to explain the reason.

```d
module test;
import std.ascii;           // std.ascii.isControl
import std.uni : isControl; // std.uni.isControl
void main()
{
    dchar c = '\n';
    assert(isControl(c));   // [a] which isControl is called?
}
```

Currently the selective import `import std.uni : isControl;` behaves as like:

```d
import std.uni;
alias isControl = std.uni.isControl;
// insert alias in imported scope implicitly
```

Then [a] always calls `std.uni.isControl`.

But, this behavior is obviously hard to understand for D newbies.
Most of programmers would imagine that 'selective import' would just add a symbol visibility in imported scope. But contrary to their mind, it behaves intrusively.
To understand precise behavior, they should learn a feature that merging overload by using alias declaration.

```d
void foo() {}
void bar(int) {}
alias baz = foo;
alias baz = bar;    // make one overloaded name 'baz'
baz();  // calls foo()
baz(1); // calls bar(1)
```

------

And also, this behavior would make selective import invconvenient.
Selective import is useful to reduce dependencies between modules, but
the implicit alias would sometimes add unintended overload.

```d
module test;
import std.ascii/* : isControl*/;
bool isControl(uint value) { return value > 0; }
import std.stdio;
void main(string[] args)
{
    dchar sw;
    stdin.readf("%s", &sw); // input "1"
    writefln("0x%x", sw);  // prints "0x31"
    assert(isControl(sw));
}
```

`isControl(sw)` intends to call `test.isControl`, but when you change the basic import to selective,
it would be suddenly changed to assert in run-time, instead of making "ambiguous function call" error.

Therefore, currently we should avoid to change basic imports to selective, because it's jsut risky.
I think we should fix this *bug*.