__traits(allMembers) includes weird symbols for structs with tuples

[Steven Schveighoffer]

This:

```d
struct S(A...)
{
     A args;
}

void main()
{
     pragma(msg, __traits(allMembers, S!(int, float)));
}
```

outputs this:

```
tuple("args", "__args_field_0", "__args_field_1")
```

What happens if you try to access __args_field_0, etc?

```d
void main()
{
    S!(int, float) s;
    import std.stdio;
    writeln(s.__args_field_0); // Error: no property __args_field_0 for 
type S!(int, float)
    writeln(__traits(getMember, s, "__args_field_0")); // same error

    pragma(msg, __traits(identifier, __traits(getMember, typeof(s), 
"__args_field_0"))); // same error
}
```

Why is __traits(allMembers) returning things that aren't members in any 
way, shape or form?

Bug?

-Steve