feat(editor): the joints check finds the tracks lying off the terrain model

The joints check also compares the tracks with the terrain model (NMT), every 5 m. Bridges, tunnels and tracks over others are left out.
- Each path lying higher or lower than the model by more than the threshold (0.5 m by default) is listed once, at its farthest place off.
- The places are compared with the same offset the model has against the scenery; a scenery not fitted to the model as a whole is measured about its median.
- The squares of the model are loaded in the background, and the check waits for them with a progress bar.
- These entries can't be fixed from the list. In the top view, the overlay shows the issues over the whole screen.
- Self-test: jointsmodel <threshold>.

lang/editor_pl.po

@@ -9898,3 +9898,24 @@ msgstr "Podsypka"
 
 msgid "Off: the top view draws the rails and sleepers of the tracks without the ballast, so the ground under them shows"
 msgstr "Wyłączone: widok z góry rysuje szyny i podkłady bez podsypki, widać teren pod torami"
+
+msgid "off the terrain model"
+msgstr "odstaje od NMT"
+
+msgid ", the terrain model left out: the scenery isn't placed on the map (the orthophoto settings)"
+msgstr ", bez NMT: sceneria nie jest umieszczona na mapie (ustawienia ortofotomapy)"
+
+msgid ", %d paths off the terrain model"
+msgstr ", odstające od NMT: %d"
+
+msgid "Terrain model %zu / %zu"
+msgstr "NMT %zu / %zu"
+
+msgid "Off the terrain model (m)"
+msgstr "Odstaje od NMT o (m)"
+
+msgid "The track lies higher or lower than the terrain model (NMT) says the ground is, by more than this.\nEach path is listed once, at its place the farthest off; bridges and tunnels are left out"
+msgstr "Tor leży wyżej lub niżej, niż według NMT jest grunt, o więcej niż tyle.\nKażdy tor jest na liście raz, w miejscu, gdzie odstaje najbardziej; mosty i tunele są pominięte"
+
+msgid "Against the terrain model"
+msgstr "Także względem NMT"