Allow calibrating the motionEngine when only one finger is on screen: this allows to fly the drone without the yaw, only with thrust + pitch and roll coming from the motionLink.
Simplify implementation of MotionLink: the way data is being requested at the moment is by polling, not callback.
Update Xcode project to recommended settings.
Stop sending data at init of the CrazyFlie.swift: at that moment the BluetoothLink is not even ready. Start sending it on successful bluetooth connection.