Update to rxjs 6.3.3. Use prettier to format.

[deanrad]

Manuel - you don't know how much your work here has been an inspiration for at least 2 years now. I finally am doing some stuff with RxJS for real and want to use this as a demo. I'd like your permission, and if you'd give a mention that'd be great.

It's currently deployed here with some of my cosmetics. I'd like to use this as an example in my Rx-wrapper project Antares which aims to make event driven programming easier.

[Lorti]

Thank you for your kind words and the long overdue update to the latest RxJS! 🙇‍♂️

That's a lot of changes, it may take some time until I find the time to review them, but I'm looking forward to it.

Of course you're free to do whatever you want with my open-source code, no need to ask for permission.