Graphs have customizable line colors and integrated legend

Graphs not only have customized line colors, but those colors are used as part the generated legend!
That's *two* merge requests for the price of *one*! :+1:

Also did some minor formatting and code cleanup.
[#74535922]
[#74536668]
Note that Browserify is specified as dependency in package.json. What you have to do is just to run `npm install` and it will make sure that all dependencies are available.