Switch to using a singleton

The reason for this is that the object needs to stay accessible
because adding a block into the world is done by the object
that was used to register it in the game registry, not by the type.

src/main/java/lostcave/deathchests/DeathChests.java

@@ -46,7 +46,9 @@ public class DeathChests {
     @EventHandler
     public void init(FMLInitializationEvent event) {
         Debug.out("Received FMLInitializationEvent");
-        GameRegistry.registerBlock(new BlockDeathChest(), "death_chest");
+
+        GameRegistry.registerBlock(BlockDeathChest.getInstance(), "death_chest");
+
         // TODO (probably here): Add death event handler
     }
 

src/main/java/lostcave/deathchests/block/BlockDeathChest.java

@@ -4,7 +4,13 @@ import net.minecraft.block.BlockChest;
 
 public class BlockDeathChest extends BlockChest {
 
-    public BlockDeathChest() {
+    private static final BlockDeathChest instance = new BlockDeathChest();
+
+    public static BlockDeathChest getInstance() {
+        return instance;
+    }
+
+    private BlockDeathChest() {
         super(0);
         this.setBlockName("death_chest");
     }