Spent some more hours in generic hell. Chose a cleaner approach to receive the generic type of a filter by asking for an explicit type instead of reading it from the subclass.
Changed interface signature to avoid returning of raw types by ElementNode iterator.
Fixed some generic errors.
Clean up of class source code.
Added simple Ajax support.
Added more Ajax support.
Another clean up of the generic definitions.
Added some interface types to allow easier handling of selections. Finished refactorization of generic types.