Add '#' wildcard to support the hokey but useful Map to Array transform

[milosimpson]

Currently Jolt can transform Arrays into Maps, but it can't do the opposite of transforming a Map into an Array.

The idea is to add an implicit counter that can be be used to "auto generate" array indices.

The usecase is hokey, in that Map to Array transform will not have a guaranteed order, but sometimes there doesn't need to be an order.