Support delegation properties

As atomic document says to leak atomic values to public use:

```kotlin
val _pref = atomic(0L)
var pref : Long
    get() = _pref.value
    set(value) { _pref.value = value }
```

so I think it's possible to have something like:

```kotlin
val pref by atomicVar(0L)
val pref by atomicVal(0L)

this::pref.atomic.value = 10
```