Enhance the racing aspet - make them sceanrios

[CurryKitten]

I don't really like racing, but I do like the idea of a sort of adventure course where you are trying to get around a circuit which forces you down tricky to fly areas - rather than just flying between hoops. The intention here is to add to the scenarios page and then dynamically add the racecourse depending on which is chosen. I'd like the option of some sort of navigation help so people never feel lost, and we'll need a timer in place as well.

[CurryKitten]

There was a great idea opened in issue #61 about using pylons instead of gates for beginners as it doesn't force them to fly too close to the ground. I need to incorporate this into the redesign of the racing - with pylons giving the easiest way through and smaller gates being the more difficult.