Support use of any coordinate system supported by Webots

[brettle]

PR #75 changed the example world to use the default Webots coordinate system but that should not be a requirement. The user should be able to define their world/robot using whichever coordinate system they prefer and the values returned by DeepBlueSim should still be correct. This will require DeepBlueSim to detect which coordinate system Webots is using and convert from it to the correct coordinate system for the device. It might make sense for this to go through an intermediate coordinate system which corresponds to the wpilib's default NWU coordinate system.