Comet Leonard and a big refactoring

Over the last year I've been gradually converting it to Kotlin and cleaning up some of the code. The codebase has always been a bit of a tangled mess because we threw it together in a hurry. Back in 2009 most of our energy was absorbed in just figuring out how Android and its sensors worked, mostly by trial and error. There wasn't much time for design or style. During the clean up I must have discovered 3 different methods for converting a vector into Ra and Dec, or bounding an angle between 0 and 2 Pi etc. Duplication is everywhere. There's still a long way to go...but I finally feel confident enough to add a new feature, albeit a modest one.
More to come.