Port to GTK4

GTK3

GTK4

pi2-demo/src/Map.cpp

@@ -16,6 +16,9 @@
 
 Map::Map(std::istream &is, std::string_view windowTitle)
     : time(0), mapWindow(windowTitle) {
+  // Make sure to recognize `.` as decimal mark
+  is.imbue(std::locale::classic());
+
   std::string type;
   while (is >> type) {
     if (type == "KREUZUNG") {