Camera path update

Yo, updated the camera path stuff.  Saves out to json now so maybe you can have a go reading it in?  It'll need more complexity, for things like camera framing, speed of the camera, and also maybe the ability to support branches? Like, non-linearity, so you can complete the level via a number of different paths.  But that's maybe thinking too far ahead.  

Been having some trouble with crashing when I try and clean-up objects as they get deleted, but maybe we can have a look at that tomorrow?  Not sure how Qt handles garbage-collection stuff...