Feature: Show Outings from linked itineraries

There is an inconsistency:

* Waypoints show outings from all linked routes
* Routes themselves only show their own outings and not outings from linked routes

Usually, linked routes are "related" eg share a big part of the route, so conditions of outings on linked routes will be very relevants.

Possible designs:

* Show them mixed together (same as waypoint) and rely on outing names to reduce confusion
* Show them in a separate section