Remove height from //expand vert.

With new world height limits, this will cause more confusion than good.
`//outset -v` or `//expand u,d` can replicate the previous behavior.

worldedit-core/src/main/java/com/sk89q/worldedit/command/ExpandCommands.java

@@ -19,18 +19,15 @@
 
 package com.sk89q.worldedit.command;
 
-import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.sk89q.worldedit.IncompleteRegionException;
 import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.WorldEditException;
-import com.sk89q.worldedit.command.argument.HeightConverter;
 import com.sk89q.worldedit.command.util.Logging;
 import com.sk89q.worldedit.command.util.PermissionCondition;
 import com.sk89q.worldedit.extension.platform.Actor;
 import com.sk89q.worldedit.internal.annotation.Direction;
 import com.sk89q.worldedit.internal.annotation.MultiDirection;
-import com.sk89q.worldedit.internal.annotation.VertHeight;
 import com.sk89q.worldedit.internal.command.CommandRegistrationHandler;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.regions.Region;
@@ -44,15 +41,12 @@
 import org.enginehub.piston.annotation.CommandContainer;
 import org.enginehub.piston.annotation.param.Arg;
 import org.enginehub.piston.inject.Key;
-import org.enginehub.piston.part.CommandArgument;
 import org.enginehub.piston.part.SubCommandPart;
 
 import java.util.List;
 
 import static com.sk89q.worldedit.command.util.Logging.LogMode.REGION;
 import static com.sk89q.worldedit.internal.command.CommandUtil.requireIV;
-import static java.util.Objects.requireNonNull;
-import static org.enginehub.piston.part.CommandParts.arg;
 
 /**
  * Extracted from {@link SelectionCommands} to allow importing of {@link Command}.
@@ -93,32 +87,22 @@ public static void register(CommandRegistrationHandler registration,
     }
 
     private static Command createVertCommand(CommandManager commandManager) {
-        CommandArgument heightPart = arg(
-            TranslatableComponent.of("height"),
-            TextComponent.of("The height to expand both upwards and downwards")
-        )
-            .defaultsTo(ImmutableList.of(HeightConverter.DEFAULT_VALUE))
-            .build();
         return commandManager.newCommand("vert")
-            .addPart(heightPart)
             .description(TranslatableComponent.of("worldedit.expand.description.vert"))
             .action(parameters -> {
-                int height = requireNonNull(parameters.valueOf(heightPart)
-                    .asSingle(Key.of(int.class, VertHeight.class)));
                 expandVert(
                     requireIV(Key.of(LocalSession.class), "localSession", parameters),
                     requireIV(Key.of(Actor.class), "actor", parameters),
-                    requireIV(Key.of(World.class), "world", parameters),
+                    requireIV(Key.of(World.class), "world", parameters)
-                    height
                 );
                 return 1;
             })
             .build();
     }
 
-    private static void expandVert(LocalSession session, Actor actor, World world,
+    private static void expandVert(LocalSession session, Actor actor, World world) throws IncompleteRegionException {
-                                   int height) throws IncompleteRegionException {
         Region region = session.getSelection(world);
+        int height = world.getMaxY() - world.getMinY();
         try {
             long oldSize = region.getVolume();
             region.expand(