nbt support WIP and proper container API

src/main/java/carpet/script/value/Value.java

@@ -173,11 +173,6 @@ public abstract class Value implements Comparable<Value>, Cloneable
         return (long)readNumber();
     }
 
-    public Value getElementAt(Value v2)
-    {
-        throw new InternalExpressionException("get element can only be obtained for lists and nbt values");
-    }
-
     public String getTypeString()
     {
         throw new InternalExpressionException("How did you get here? Cannot get type of an intenal type.");