Batch update/insert for stores

[fullben]

Currently, new values can only be added to stores by calling the update(K key, TV value) method.

Would it be possible to implement a method along the signature of void update(Function<TV, K> keyFunction, Collection<TV> value) for batch inserts?

[JanWiemer]

Good idea! I added an issue for this: #23 (comment)
I will try to do this in the near future...