Fix Craft Entity constructors and toStrings.

Also, standardise getHandle and clean up in general.
getHandle is now using the 'entity' member variable instead of
super.getHandle, as this reduces the number of chained calls needed.

src/main/java/org/bukkit/craftbukkit/entity/CraftEnderSignal.java

@@ -1,14 +1,19 @@
 package org.bukkit.craftbukkit.entity;
 
-import net.minecraft.server.Entity;
+import net.minecraft.server.EntityEnderSignal;
 import org.bukkit.craftbukkit.CraftServer;
 import org.bukkit.entity.EnderSignal;
 
 public class CraftEnderSignal extends CraftEntity implements EnderSignal {
-    public CraftEnderSignal(CraftServer server, Entity entity) {
+    public CraftEnderSignal(CraftServer server, EntityEnderSignal entity) {
         super(server, entity);
     }
 
+    @Override
+    public EntityEnderSignal getHandle() {
+        return (EntityEnderSignal) entity;
+    }
+
     @Override
     public String toString() {
         return "CraftEnderSignal";