Native JavaScript operations

[mike-mcgann]

Two features do not work in the web version:

• timezone conversions
• coordinate transforms

The timezone conversion requires access to the timezone database which isn't available through the WASM runtime and the coordinate transforms rely on a C library which doesn't get converted to WASM. For situations like these, having a native JavaScript implementation provide the operation would be great when it could be implemented that way.

This code would need tests, which would require setting up a JS test suite, which is probably a good idea so that the interface parts could be tested was well where needed.