Generic classes

[thosakwe]

Once #5 is ready, maybe add generics:

abstract class List<T> {
  size():int;
  add(item:T):void;
  get(index:int):T;
  remove(index:int):T;
}

class ArrayList<T> implements List<T> {
  let _items = T [];

  @override()
  size():int => Lists.size(_items);

  @override()
  add(item:T):void {
    _items = Lists.add(_items, item);
  }

  @override()
  get(index:int):void {
    if (index >= Lists.size(_items))
      throw new RangeError('Out of range');
    return _items[index];
  }

  @override()
  remove(item:T):void {
    // Complex logic...
  }
}

This will probably require a BonoboGenericType that can resolve type parameters, and throw errors if none are defined.