Hi there!

[benwainwright]

Really nice plugin! I thought I'd spend a bit of time implementing one of the features on your wishlist, because with a bit of work I can really see myself using this plugin in my workflow. I'd love to see this merged, so let me know if you'd like me to change anything

Changes in this PR

• Added TypeScript compile to the prepare hook (webpack doesn't do type checking, so there were lots of type errors)
• Fixed all the type errors
• Formatted the code with prettier
• Add sign in the gutter at the start of a test when it passes or fails
• Parse the actual assertion failure location out of the error message and use that to place your diagnostic
• Add some status bar messages so the user knows what is going on