Mapgen: Make mgv7 the default in UI

The actual menu default comes from defaultsettings.cpp.

Author: sofar

builtin/settingtypes.txt

@@ -862,7 +862,7 @@ block_send_optimize_distance (block send optimize distance) int 4 2
 
 #    Name of map generator to be used when creating a new world.
 #    Creating a world in the main menu will override this.
-mg_name (Mapgen name) enum v6 v5,v6,v7,flat,valleys,fractal,singlenode
+mg_name (Mapgen name) enum v7 v5,v6,v7,flat,valleys,fractal,singlenode
 
 #    Water surface level of the world.
 water_level (Water level) int 1

minetest.conf.example

@@ -1053,7 +1053,7 @@
 #    Name of map generator to be used when creating a new world.
 #    Creating a world in the main menu will override this.
 #    type: enum values: v5, v6, v7, flat, valleys, fractal, singlenode
-# mg_name = v6
+# mg_name = v7
 
 #    Water surface level of the world.
 #    type: int

src/defaultsettings.cpp

@@ -327,7 +327,7 @@ void set_default_settings(Settings *settings)
 	settings->setDefault("liquid_update", "1.0");
 
 	//mapgen stuff
-	settings->setDefault("mg_name", "v6");
+	settings->setDefault("mg_name", "v7");
 	settings->setDefault("water_level", "1");
 	settings->setDefault("chunksize", "5");
 	settings->setDefault("mg_flags", "dungeons");