“Out” parameters and destructors

[Ogion]

Functions with `out` parameters simply initialize the parameter 
with `.init`, instead of properly destroying it.

```D
import std.stdio;

int count;

struct S {
     bool initialized;
     this(int) {
         writeln("S()");
         initialized = true;
         count++;
     }
     ~this() {
         if (initialized) {
             writeln("~S()");
             count--;
         }
     }
}

void foo(out S s) {
     s = S(42);
}

void bar() {
     S s;
     foo(s);
     foo(s);
}

void main() {
     bar();
     writeln(count);
}
```

Output:
```
S()
S()
~S()
1
```

Looks like a serious oversight.