Improve logging & debugging

For now, logging & debugging is not persistent and can be a bit tricky. If I want to debug a component over a certain time range, I've to manually set the debug mode in the component script / template. If I don't do that, I've to set debug mode each time I reload the browser.

This is doable, but the UX is not very nice and people can accidentaly commit debug modes to Git.

Let's refactor that, so that we've a persistent debug mode via local storage.