Create a typed ItemStack array when writing it to a field. FIXES 24.

After the package versioning commit, ProtocolLib switched to performing
everything exclusively with reflection. Unfortunately, this may have
introduced a couple of new bugs.

This problem is caused by the fact that ProtocolLib converts a Bukkit
ItemStack array to an Object array instead of an array of NMS 
ItemStacks. This object array can't be assigned to a ItemStack array,
so the write operation fails.

The fix is to create a typed array with reflection.

ProtocolLib/src/main/java/com/comphenix/protocol/events/PacketContainer.java

@@ -25,6 +25,7 @@ import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.io.Serializable;
+import java.lang.reflect.Array;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.Collection;
@@ -241,12 +242,12 @@ public class PacketContainer implements Serializable {
 				BukkitConverters.getIgnoreNull(new EquivalentConverter<ItemStack[]>() {
 					
 			public Object getGeneric(Class<?>genericType, ItemStack[] specific) {
-				Object[] result = new Object[specific.length];
+				Class<?> nmsStack = MinecraftReflection.getItemStackClass();
+				Object[] result = (Object[]) Array.newInstance(nmsStack, specific.length);
 				
 				// Unwrap every item
 				for (int i = 0; i < result.length; i++) {
-					result[i] = stackConverter.getGeneric(
-							MinecraftReflection.getItemStackClass(), specific[i]); 
+					result[i] = stackConverter.getGeneric(nmsStack, specific[i]); 
 				}
 				return result;
 			}

ProtocolLib/src/main/java/com/comphenix/protocol/utility/MinecraftReflection.java

@@ -314,12 +314,12 @@ public class MinecraftReflection {
 	 * @return The NetHandler class.
 	 */
 	public static Class<?> getNetHandlerClass() {
-		return getMinecraftClass("NetHandler");
+		return getMinecraftClass("NetHandler", "Connection");
 	}
 	
 	/**
-	 * Retrieve the NetLoginHandler class.
-	 * @return The NetLoginHandler class.
+	 * Retrieve the NMS ItemStack class.
+	 * @return The ItemStack class.
 	 */
 	@SuppressWarnings("rawtypes")
 	public static Class getItemStackClass() {