feat: surface decoration generation but only in even chunks

common/api/src/main/java/com/dfsek/terra/api/block/BlockType.java

@@ -13,6 +13,9 @@ import com.dfsek.terra.api.block.state.BlockState;
 
 /**
  * Represents a type of block
+ * <p>
+ * Important! You <b>need</b> to implement a proper equals() and hashCode() here in
+ * your platform implementation for surface decorations to show up
  */
 public interface BlockType extends Handle {
     /**