Better list support

[thosakwe]

Requires #14, as well as #15.

abstract final class Lists {
  @external()
  static emptyList<T>():T[];

  @external()
  static create<T>(size:int):T[];

  @external()
  static fill<T>(list:T[], value:T):void;

  @external()
  static copy<T>(from:T[], to:T[], offset:int, len:int):void;

  @external()
  static size<T>(list:T[]):int;

  static duplicate<T>(list:T[]):T[] {
    let sz = size(list);
    let result = create(sz);
    copy(list, result, 0, sz);
    return result;
  }

  static add<T>(list:T[], value:T):T[] {
    let sz = size(list);
    let result = create(sz + 1);
    copy(list, result, 0, sz);
    result[sz] = value;
    return result;
  }
}
// And more...