Update mapgen.cpp

src/mapgen.cpp

@@ -41,7 +41,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "log.h"
 #include "mapgen_flat.h"
 #include "mapgen_fractal.h"
-#include "mapgen_v5.h"
+#include "mapgen_torus.h"
 #include "mapgen_v6.h"
 #include "mapgen_v7.h"
 #include "mapgen_valleys.h"
@@ -78,7 +78,7 @@ struct MapgenDesc {
 ////
 
 static MapgenDesc g_reg_mapgens[] = {
-	{"v5",         true},
+	{"MathWorlds",         true},
 	{"v6",         true},
 	{"v7",         true},
 	{"flat",       true},