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/CraftEnderDragonPart.java

@@ -1,17 +1,27 @@
 package org.bukkit.craftbukkit.entity;
 
-import net.minecraft.server.Entity;
+import net.minecraft.server.EntityComplexPart;
 import org.bukkit.craftbukkit.CraftServer;
 import org.bukkit.entity.EnderDragon;
 import org.bukkit.entity.EnderDragonPart;
 
 public class CraftEnderDragonPart extends CraftComplexPart implements EnderDragonPart {
-    public CraftEnderDragonPart(CraftServer server, Entity entity) {
+    public CraftEnderDragonPart(CraftServer server, EntityComplexPart entity) {
         super(server, entity);
     }
 
     @Override
     public EnderDragon getParent() {
-        return (EnderDragon)super.getParent();
+        return (EnderDragon) super.getParent();
+    }
+
+    @Override
+    public EntityComplexPart getHandle() {
+        return (EntityComplexPart) entity;
+    }
+
+    @Override
+    public String toString() {
+        return "CraftEnderDragonPart";
     }
 }