Added ItemStep for diff visibility.

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

@@ -0,0 +1,50 @@
+package net.minecraft.server;
+
+public class ItemStep extends ItemBlock {
+
+    public ItemStep(int i) {
+        super(i);
+        this.setMaxDurability(0);
+        this.a(true);
+    }
+
+    public int filterData(int i) {
+        return i;
+    }
+
+    public String a(ItemStack itemstack) {
+        int i = itemstack.getData();
+
+        if (i < 0 || i >= BlockStep.a.length) {
+            i = 0;
+        }
+
+        return super.getName() + "." + BlockStep.a[i];
+    }
+
+    public boolean a(ItemStack itemstack, EntityHuman entityhuman, World world, int i, int j, int k, int l) {
+        if (l != 1) {
+            ;
+        }
+
+        if (itemstack.count == 0) {
+            return false;
+        } else if (!entityhuman.d(i, j, k)) {
+            return false;
+        } else {
+            int i1 = world.getTypeId(i, j, k);
+            int j1 = world.getData(i, j, k);
+
+            if (l == 1 && i1 == Block.STEP.id && j1 == itemstack.getData()) {
+                if (world.setTypeIdAndData(i, j, k, Block.DOUBLE_STEP.id, j1)) {
+                    world.makeSound((double) ((float) i + 0.5F), (double) ((float) j + 0.5F), (double) ((float) k + 0.5F), Block.DOUBLE_STEP.stepSound.getName(), (Block.DOUBLE_STEP.stepSound.getVolume1() + 1.0F) / 2.0F, Block.DOUBLE_STEP.stepSound.getVolume2() * 0.8F);
+                    --itemstack.count;
+                }
+
+                return true;
+            } else {
+                return super.a(itemstack, entityhuman, world, i, j, k, l);
+            }
+        }
+    }
+}