[Tagging] route/forward/backward members in all types of routes

[Tijmen Stam]

> Very well. It seems to me that a role such as "route" in PTv1 exists
> only for clarity, as it would be equivalent to an empty role. Could we
> say that "forward" also can be optionally added in PTv2 for clarity?

No.

The forward/backward is not relative to the direction of the _route_, but
relative to the direction of a _way_.

So even if you have an outbound (say "forward")/inbound (say "backward")
routes, then the outbound route going over a way against the direction of
that way should have the backward role, NOT the forward one as would be
intuitive.

In PTv2 only a few roles are acceptable: stop and platform (and the
equivalents stop_exit_only and stop_entry_only) for stops and platforms,
and _no role_ for the ways in the route.

Even if there were a logical ordering between the outbound and inbound
route, then that can be arranged by the ordering of the routes in the
route_master relation (not that I know of any implied meaning of such an
ordering).