Add RecordMapper<E>, similar to RecordHandler<R>, mapping records to custom types

[lukaseder]

The current RecordHandler type is used as a "sink" receiving records, returning void:

create.selectFrom(BOOK).fetchInto(new RecordHandler<BookRecord>() {
    public void next(BookRecord record) {
        dothings(record);
    }
});

A RecordMapper on the other hand, transforms record into another type. For instance:

List<Integer> result = 
create.selectFrom(BOOK).fetchInto(new RecordMapper<BookRecord, Integer>() {
    public Integer map(BookRecord record) {
        return dothings(record);
    }
});

Possibly, all other into(Class<E>) methods should be refactored to use RecordMapper types instead, e.g. a POJORecordMapper

[lukaseder]

@idugic : I'm taking this one back, as I need this for another implementation