Fixes #675 No disabled feature should log spam or crash anymore.

Deprecates the old usage of the AEItemDefinitions via the direct method access of

* blocks()
* parts()
* items()
* materials()

and thus use the new re-direct via definitions().

All definitions are now initialized, no matter what. But SubItems, Items and Blocks are not registered, if by chance are disabled.

src/main/java/appeng/core/CreativeTabFacade.java

@@ -19,9 +19,12 @@
 package appeng.core;
 
 import net.minecraft.creativetab.CreativeTabs;
+import net.minecraft.init.Blocks;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
 
+import com.google.common.base.Optional;
+
 import appeng.api.AEApi;
 import appeng.items.parts.ItemFacade;
 
@@ -43,7 +46,13 @@ public final class CreativeTabFacade extends CreativeTabs
 	@Override
 	public ItemStack getIconItemStack()
 	{
-		return ((ItemFacade) AEApi.instance().items().itemFacade.item()).getCreativeTabIcon();
+		final Optional<Item> maybeFacade = AEApi.instance().definitions().items().facade().maybeItem();
+		if ( maybeFacade.isPresent() )
+		{
+			return ((ItemFacade) maybeFacade.get()).getCreativeTabIcon();
+		}
+
+		return new ItemStack( Blocks.planks );
 	}
 
 	public static void init()