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/editorProfile.hpp

@@ -30,7 +30,8 @@ struct pvi
 struct limits
 {
 	double grade_max{6.0}; // per mille
-	double grade_switch_max{2.5}; // per mille, over switches
+	double grade_switch_max{0.0}; // per mille, over switches and their shared timbers; 0: the limit of the line, as a switch may lie on
+	                              // the grade of the line. A lower one for the tracks of a station where vehicles stand
 	double radius_factor{0.4}; // R >= k * V^2
 	double radius_min{2000.0};
 	double curve_threshold{2.0}; // per mille, change of grade which needs a vertical curve
@@ -107,18 +108,43 @@ struct recognition
 	double grade_tolerance{0.0004};
 	double minimum_length{15.0};
 	double sharp_gap{2.0};
+	double step{0.02};
+	// where the line read departs from the track by more than this, the bends of the track itself; 0 leaves the line as read
+	double detail{0.0};
 };
 // grade line of existing track, from its elevations and grades sampled along the chainage
 line recognize(std::vector<double> const &Chainages, std::vector<double> const &Elevations, std::vector<double> const &Grades, recognition const &Options);
 
 struct ground_fit
 {
-	double tolerance{1.0}; // m, departure from the ground which doesn't yet need a change of grade
-	double smoothing{20.0}; // m, length over which the ground is averaged
+	double tolerance{1.0}; // m, the ground this near the line agrees with it; farther, the line doesn't lie on it there
+	double grade_max{0.0}; // per mille, the steepest grade the line may take; 0: the limit of the line
+	// heights the line keeps between before it lies on the ground, as where the tracks off a switch of it lead into another line:
+	// they can't climb more than their length lets them
+	struct bound
+	{
+		double chainage{0.0};
+		double low{0.0};
+		double high{0.0};
+	};
+	std::vector<bound> bounds;
 };
-// grade line which follows the ground within the limits of Settings, with the least earthworks.
-// Ground is NaN where there's none; the joined ends of the route keep the elevation of the adjoining track
-line fit_ground(std::vector<double> const &Chainages, std::vector<double> const &Ground, context const &Context, line const &Settings, ground_fit const &Options);
+// grade line which lies on the ground where it agrees, within the limits of Settings, with the fewest and least changes of
+// grade; where the ground parts from it, at a bridge, a viaduct, a cutting wall, the line goes on past it. Chainages ascend,
+// Ground is NaN where there's none. Each sample may have its own tolerance, how closely it tells the height, and its own
+// reach, how far from the line it still belongs to it (empty: the tolerance of Options). The joined ends of the route keep
+// the elevation of the adjoining track, and its grade where the line can take it over
+line fit_ground(std::vector<double> const &Chainages, std::vector<double> const &Ground, context const &Context, line const &Settings, ground_fit const &Options, std::vector<double> const &Tolerances = {},
+                std::vector<double> const &Reaches = {});
+// stretches where the ground departs from the line by over Tolerance, one way all along: depth below the line (a gap, under
+// a bridge, a viaduct), above it (a wall, a structure over the track)
+struct departure
+{
+	double from{0.0};
+	double to{0.0};
+	double depth{0.0}; // m, the ground against the line where they part the most
+};
+std::vector<departure> departures(line const &Line, std::vector<double> const &Chainages, std::vector<double> const &Ground, double const Tolerance);
 
 // chainages where the paths have to end so that each of them carries a single grade or a single curve
 std::vector<double> breaks(line const &Line);