Rebuilt with 10.14 SDK.

Fixes an issue with Django U2F support.

Adds back support for the 1.0 version of the JS API.
Hopefully also fixes some code-signing issues.

This version sees a major rewrite of both the JS and Swift code, and it based off the issue/39-implement-low-level-api branch.

Major changes:

• the high level javascript implementation is now a lot closer to the reference implementation, and works in terms of the low level spec
• the extension now effectively implements the low level spec, which means that sites which only want to work with it can
• the script is injected using the beforeload event, which means that the injecting happens earlier; hopefully this will improve detection of the polyfill

Another small fix to getApiVersion.

Another attempt at implementing getApiVersion.

Implements u2f.getApiVersion.
Some minor cleanup of the injected javascript.

A few tweaks and fixes. Working again for the test site. Still issues with github.com.

This is an experimental release which incorporates a refactor of the original Swift code, plus a few bug fixes and other changes from the master branch.

I can't guarantee that this build is working, but I'm uploading it for testing.

Hey, it's working!