Add -editor startup so the exe comes up straight in the editor

The editor was reachable only from the driver mode with F11, which meant
loading a scenario and starting the whole simulation first. With -editor
the scenario loader hands over to the editor instead of the driver, so
physics, AI and timetables never run - only the loaded world is there to
be worked on.

Without -s the scenery from eu07.ini is used, falling back to pusta.scn
when the ini names none. F11 quits instead of popping the mode, since the
editor is now the bottom of the mode stack and popping it would leave the
rest of the frame reading an empty one. Editor entry forces free-fly even
with no vehicle to leave.

utilities/Globals.h

@@ -77,6 +77,8 @@ struct global_settings {
     std::string szTexturesDDS{ ".dds" }; // lista tekstur od DDS
     std::string szDefaultExt{ szTexturesDDS };
 	std::string SceneryFile;
+    // uruchomienie prosto do edytora, z pominięciem symulacji; edytor jest wtedy trybem podstawowym
+    bool editor_startup{ false };
     std::string local_start_vehicle{ "EU07-424" };
     int iConvertModels{ 0 }; // tworzenie plików binarnych
     int iConvertIndexRange{ 1000 }; // range of duplicate vertex scan