feat(track): 3D sleepers and switch timbers, blade heel and throw from templates, one rail carving pass

- sleepers3d / sleepers3dplain / sleepers3dbed in eu07.ini: timbers put together from the begin, main and end parts of a model
  and stretched to their length, plain sleepers of their own model; tracks whose plain sleepers would touch are laid as one
  cluster, lines of timbers led by priority and turned to the bisectors of frogs and crossings at a limited rate, whole timbers
  under crossings, split ones between tracks with room to part them, gaps filled per rail and overlaps shortened or dropped;
  clusters worked out in a background thread while driving, on demand in the editor
- the ballast can be left out under the beams (sleepers3dbed no)
- blades get their heel and throw from the switch template or blades <heel> <throw> in the scenery; blades of double switches
  run on into the track linking them to the next switch
- rail cutting at frogs, wing rails, movable noses and switch crossings done by one carving pass (RailCarve)
- tint of the rail treads applied to the colour only, without the matte band at the frog
- a switch trailed through with a movable nose set the other way derails the vehicle
- self-tests: sleepercheck, sharedzones, beamsnear, throw, sleepersbg

application/editoruilayer.cpp

@@ -589,6 +589,9 @@ void editor_ui::register_settings()
 
 void editor_ui::render_()
 {
+	// the keyboard navigation of ImGui is off, so Esc would not close an open list or menu by itself
+	if (ImGui::IsKeyPressed(ImGuiKey_Escape, false) && ImGui::IsPopupOpen("", ImGuiPopupFlags_AnyPopupId | ImGuiPopupFlags_AnyPopupLevel))
+		ImGui::ClosePopupsExceptModals();
 	auto *viewport{ImGui::GetMainViewport()};
 	auto const flags{ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_MenuBar};
 	// the fields of work of the editor under the menu, in a row twice as high; the tools of the one chosen in the toolbar under it