Various typescript fixes, updated all dependencies, package.json cleanup

[jpoppe]

I had some issues getting this package to compile, got various Typescript errors, etc., probably because I use a recent Node version.

In those commits I have updated all dependencies, fixed the Typescript errors to make it run and added a client command to package.json so you could run the client with ts-node with: yarn run client

[mikestead]

@jpoppe Thanks for these updates. On vacation 🌴 at the moment but will take a look in a week or so when I'm back. On surface all looks good 👍

[jpoppe]

@jpoppe Thanks for these updates. On vacation at the moment

Don't hurry ;), enjoy your holiday!