feat(editor): the curves of the laying from the photo in the design of the lines: a vertex of two transition curves meeting at its radius, with no arc and no cant, kept in the scenery files; the bends of straights eased with them at a radius from 6000 down to 3000 m, or larger where they'd be too short for the speed, else with an arc of the norms as large as fits, the straights between two bends shared, the bends staying where they were clicked and a curve below the norms kept with its warnings; a stretch traced on the photo fitted with a straight, a curve with its radius and the length of its transitions, a compound one, or two curves with a straight between them, on a thread of its own while the cursor moves; the heights from point to point through all the points clicked. Unit tests of the design of the lines

tests/unit/editor_stubs.cpp

@@ -0,0 +1,13 @@
+// stand-ins for the parts of the engine which the code of the editor under test reaches for: the translations give the English
+// messages back as they are
+
+#include "stdafx.h"
+#include "utilities/translation.h"
+
+locale Translations;
+
+const char *locale::lookup_c(const char *msg, bool) { return msg; }
+
+const std::string &locale::lookup_s(const std::string &msg, bool) { return msg; }
+
+const char *locale::lookup_n(const char *singular, const char *plural, long long n) { return n == 1 ? singular : plural; }