editor_services was growing into one interface every tool depended on
whole. It splits into the roles the editor plays for its tools: the
selection, the view, the undo history, the templates by the track, the
ground with the terrain model, the track design and the guide of the
first steps. Each tool is handed only the roles it uses, so what it
depends on can be read from its constructor; editor_services stays as
the sum of the roles the editor implements.
The seventh tool out of editor_mode. It reads the selected set of tracks
and the tab shown through the services, digitizes the tracks it lays and
refreshes the plan after it sets one parallel to another. The panel shown
for two selected tracks is a public call of the tool, and the self-test
command parallel moves with it and lays the same tracks as before.
