Adding a Batch API

[vmx]

Currently the API uses an Async Iterator interface to work with multiple items. Those operations will throw once an error occurs. There a cases where more advanced error case handling is desired.

For more information about this discussion please see:

• https://gozala.hashbase.io/posts/Constraints%20of%20an%20API%20design/
• The discussion starting at docs: major API changes #191 (comment)
• docs: major API changes #191 (comment)