Upgraded getRange/query and type definitions

Caching is now available, and can be enabled with the cache flag. This uses a weak-referenced based LRFU cache that can improve performance, guarantee key correlation with object identity, and provide immediate access to put values.

The getRange function for traversing over a range of keys now uses a true snapshot-based cursor to traverse the entire range. Previously, getRange would get blocks of 100 entries and reset the cursor between retrievals so it wasn't truly snapshot based, but now getRange should return a range of entries based on the exact snapshot/state of the database at the time when it was called.

We have also improved the TypeScript type definitions and added a test for them.