feat(editor): labels for a layman, light at the start; whole sceneries fitted to the terrain model

Labels:
- every button, field, tooltip and message of the editor reread for a beginner: short nouns for the fields with the
  sentence in the tooltip, the less used options under More settings, one glossary (field of work, template, track,
  grade), sides told from directions, degrees and per mille as signs, messages built from one format string
- plural forms through STR_P; the last entry of a po file is read too, and the Polish plural rule is in the header
- lang/editor_pl.po: the code pass entries merged, 391 entries no code uses and 3 duplicates dropped
- roads: the notes and errors naming a road translated; the build options and the layout fold the texture length,
  kerb sizes, traffic share, roundabout part, height over the ground and junction speed limit under More settings, the
  lanes start folded

Grade lines fitted to the terrain model (NMT), a line or the whole scenery at once:
- fit_ground: a robust fit on nodes 5 m apart; the ground parting from the line (a bridge, a viaduct, a wall) is gone
  past rather than followed, the bends keep off the switches as far as their curves reach, a run of bends the same way
  is one point of intersection, a curve with no room is as sharp as the room lets it be
- the ends of the line and the other paths of its switches leading into lines fitted already bound the line by what
  the tracks between can climb; ends meeting in the plan, laid apart in height by hand, are joined before the run
- apply_profile: the paths are split where split_path takes the parameter (a straight was cut in the wrong place, into
  pieces of a few centimetres the game takes for zero length), no piece shorter than the margin; the paths off the
  ends of the route are brought to its height
- Bytom: 1600 lines, grade breaks at the joints 89 -> 20; Tarnowskie Gory: 848 lines, 223 -> 3; no step over 2 cm

editor/editorTrack.hpp

@@ -70,6 +70,7 @@ class editor_track
 		float sleeper_ballast{0.f};
 		std::string timber_model;
 		std::string timber_skin;
+		std::pair<std::string, int> rail_profile;
 		std::array<std::vector<std::pair<std::string, basic_event *>>, 6> events;
 		std::string name;
 	};
@@ -383,7 +384,8 @@ class editor_track
 	static double sampled_grade(std::vector<route_sample> const &Samples, double const Chainage);
 	static glm::dvec3 sampled_position(std::vector<route_sample> const &Samples, double const Chainage);
 	// grade of the path which adjoins the end of the route, positive rising along the route
-	static bool adjoining_grade(route const &Route, bool const Atend, double &Grade);
+	// Adjoining, Path, Entered: the path met, and whether it's met at its start
+	static bool adjoining_grade(route const &Route, bool const Atend, double &Grade, TTrack **Adjoining = nullptr, int *Path = nullptr, bool *Entered = nullptr);
 	// path off the route whose end no longer met the adjoining path in height
 	struct height_gap
 	{
@@ -456,10 +458,14 @@ class editor_track
 	// touching in its middle: Pass from the crossing, half of the gauge and the width of the head; a straight there when Middle < 0
 	static slip_curve slip_of(double const Radius, double const Middle, double const Angle, double const Pass, double const Lead = 0.0, double const Entry = 0.0);
 	static std::vector<switch_template> standard_switch_templates();
+	// the rail of the switch templates fitting the track, by the rail profile it's laid with; empty where the profile doesn't tell
+	static std::string rail_of(TTrack const *Track);
 	static std::optional<switch_template> template_of(switch_design::design const &Design, std::string &Error);
 	static std::vector<switch_template> find_switch_templates();
+	// the switch of the scenery as a template of its own shape; none when its tracks don't start at one point
+	static std::optional<switch_template> template_of_switch(TTrack *Track);
 	static TTrack *load_path(std::string const &Text, TTrack const &Template, std::string const &Name = {});
-	static TTrack *create_path(TTrack const &Style, segment_data const &Path);
+	static TTrack *create_path(TTrack const &Style, segment_data const &Path, std::string const &Name = {});
 	// parameters of a path laid where there's no other path to copy them from
 	struct path_style
 	{
@@ -470,7 +476,8 @@ class editor_track
 	};
 	// the path goes to the layer receiving the items created in the editor
 	static TTrack *create_path(path_style const &Style, segment_data const &Path);
-	static TTrack *split_path(TTrack &Track, double const T);
+	// Name: of the new piece, else after the track
+	static TTrack *split_path(TTrack &Track, double const T, std::string const &Name = {});
 	static double nearest_parameter(TTrack const &Track, glm::dvec3 const &Point);
 	// point of the first path at the parameter of nearest_parameter()
 	static glm::dvec3 point_at(TTrack const &Track, double const T);
@@ -480,6 +487,8 @@ class editor_track
 	static void move_straights(std::vector<straight> const &Lines, std::vector<std::pair<glm::dvec3, glm::dvec3>> const &Ends);
 	static std::vector<TTrack *> relay(chain const &Chain, std::vector<segment_data> const &Pieces, TTrack **Last = nullptr);
 	static void retire(TTrack &Track);
+	// a retired path back in the scenery, found by its name again; it's committed by the caller
+	static void revive(TTrack &Track);
 
 	static std::string material_name(material_handle const Material);
 	static material_handle fetch_material(std::string const &Name);
@@ -514,7 +523,7 @@ class editor_track
 	static void bind_switch_path(TTrack &Switch, int const Path);
 	static void store_switch_path(TTrack &Switch, int const Path);
 	static void rebuild_geometry(TTrack &Track);
-	static TTrack *clone(TTrack const &Template);
+	static TTrack *clone(TTrack const &Template, std::string const &Name = {});
 	static TTrack *load_text(std::string const &Text, TTrack const *Template, std::string const &Name);
 	static void move_straight(straight const &Line, glm::dvec3 const &Start, glm::dvec3 const &End, std::function<bool(TTrack const *)> const &Member);
 };