Removed old rendering system

Removed old rendering system. Some parts may be left over, but they
won't affect testing.
1.10-R todo tag marks things to do with rendering.

src/main/java/appeng/core/CommonHelper.java

@@ -72,7 +72,4 @@ public abstract class CommonHelper
 
 	public abstract void missingCoreMod();
 
-	public abstract void configureIcon( Object item, String name );
-
-	public abstract ResourceLocation addIcon( String string );
 }