enable hot reload

[Blueforcer]

For Apps and Core

[padarom]

Hot Reload for the Core should already work as that is just the default Nuxt feature. The core needs to be started in dev mode though, which I think can be done with npm run dev.

[padarom]

I implemented it for now as a live reload, rather than a hot reload. Hot reload would require module replacement, i.e. redefining functions that have changed since the last version. Since we are using the Vue CLI service to build apps to a UMD file, I am quite sure we can't currently get HMR changelogs, meaning I'd have to implement HMR myself, which I think is a bit above the scope of this as of right now. I'd still prefer hot reloading, but I think live reload is just a minor inconvenience in the grand scheme of things and we can try to get at proper HMR in the future.

See https://stackoverflow.com/a/24587740/3025537 as a reference to what I'm talking about.