[Suggestion] Allow choosing only trains with a seat reservation (non-9€ trains)

[schlomo]

Some people don't want to be stuffed into overfull trains and would be happy to pay for a seat...

Currently I can choose all trains or regional/local trains.

Please kindly add an option to also search for non-local trains or, to be more correct, select trains that offer a seating reservation (that way it would be useful also outside of Germany).

Thanks a lot for this extremely useful tool!