#268 introduction of qualifier

The solution is more-or less ready.

I need to add some additional tests to cover different kind of qualifying situations such as:
1. class
2. #method

Also I need to add test cases for the `@MapMapping` and `@IterableMapping`.
> A huge sorry btw. for the big delay with this :(

Ah. In that case: there are some more you should take a look at :smile:.