Dispatcher scripts that route trains at a station based on where they
go afterwards (e.g. a big terminal throat with several outbound
directions) have no way to read that: whois +40 only exposes the
current/next timetable entry (NextStop()/IsStop()), which while the
train is at that very station is that station itself.
Adds flags::whois_ahead (bit 6, previously unused) plus
TTrainParameters::StationNameAhead(Offset)/StationIsStopAhead(Offset),
returning the raw TimeTable[] entry Offset positions past StationIndex
(name and whether it's a booked stop, "none"/false past the end of the
timetable). The new whois branch calls both with Offset=1, mirroring
the existing +40 branch's UpdateValues()/WriteLog() shape.
Logic-verified with an isolated harness mirroring the touched types
(TTrainParameters/TController/TMemCell shapes and the exact function
bodies); not yet build-tested against the full engine locally - relying
on CI for that.
