get all traits of ancestor classes & ancestor traits

useful when using setters in traits
@amoniker this won't work the way you think it does... the `+=` operator only works cleanly with associative arrays, because it only **adds undefined keys**.

```php
$a = ['one' => 1, 'two' => 2] + ['three' => 3]; // works as expected
$b = [1, 2] + [3]; // yields [1, 2] because: [0 => 1, 1 => 2] + [0 => 3], and key 0 is already defined
```