@oneline UDA

`@oneline` UDA for using SDL attributes

example:
D code
```d
struct Foo
{
    string value;
    int count;
}
@oneline
Foo foo;
```
SDL file
```sdl
foo "hello" count=12
```

now need SDL like this
```sdl
foo {
    value "hello"
    count 12
}
```