Faster gets and query/range retrieval

This release includes a significant overhaul of how get and query/range retrievals are performed to reduce the amount of native calls and the number of JS objects that have to be transmitted across the native calls. This also facilitates and accompanies adding support for V8's new fast-api-calls feature, which also improves performance. This can yield over a 50% performance improvement in get operations, and over twice the speed for iterating through ranges, with small payloads where deserialization is not the dominant cost. There are also very large improvements in the performance of count operations and offset handling as well.

Also related to these changes is switching (back) to serializing and deserializing keys in JS (instead of C++), which reduces the number of JS value/objects cross the native call barrier. This also opens the door for more customized JS key serialization strategies (negation, custom UUID handlers, and potentially more performant little endian format).