Update SpongeSchematic format to version 2.

Allows saving and loading entities and biomes.

worldedit-core/src/main/java/com/sk89q/jnbt/CompoundTagBuilder.java

@@ -181,6 +181,18 @@ public class CompoundTagBuilder {
         return put(key, new StringTag(value));
     }
 
+    /**
+     * Remove the given key from the compound tag. Does nothing if the key doesn't exist.
+     *
+     * @param key the key
+     * @return this object
+     */
+    public CompoundTagBuilder remove(String key) {
+        checkNotNull(key);
+        entries.remove(key);
+        return this;
+    }
+
     /**
      * Put all the entries from the given map into this map.
      *