Convert contained worlds to Anvil (thanks to Amaranth)

src/main/java/net/minecraft/server/MinecraftServer.java

@@ -184,7 +184,7 @@ public class MinecraftServer implements Runnable, ICommandListener, IMinecraftSe
         this.t = MathHelper.a(this.t, 64, 256);
         this.propertyManager.a("max-build-height", Integer.valueOf(this.t));
         log.info("Preparing level \"" + s + "\"");
-        this.a(new WorldLoaderServer(new File(".")), s, j, worldtype);
+        this.a(new WorldLoaderServer(server.getWorldContainer()), s, j, worldtype); // CraftBukkit - world container
 
         // CraftBukkit start - display seconds for the completion time
         long elapsed = System.nanoTime() - i;
@@ -290,6 +290,11 @@ public class MinecraftServer implements Runnable, ICommandListener, IMinecraftSe
                     }
                 }
 
+                if (convertable.isConvertable(name)) {
+                    log.info("Converting map!");
+                    convertable.convert(name, new ConvertProgressUpdater(this));
+                }
+
                 world = new SecondaryWorldServer(this, new ServerNBTManager(server.getWorldContainer(), name, true), name, dimension, settings, this.worlds.get(0), org.bukkit.World.Environment.getEnvironment(dimension), gen); // CraftBukkit
             }