Closes#718. Adds five new transport reservation types alongside the
existing flight/train/car/cruise: bus, taxi, bicycle, ferry and a generic
'transport_other' catch-all. The new types are treated as first-class
transports everywhere — the transport modal, day plan, route calculation,
map overlays, file grouping and the PDF export — and are translated across
all 20 locales.
A dedicated 'transport_other' value is used for the catch-all so existing
'other' bookings are not reclassified as transport.
Maurice