Add client.enableEmergency(); functionality to trigger emergency cutout

[ColinCreamer]

It would be great if this API provided an easy way to trigger an emergency cutout while flying, to make it dead drop from the air. Similar to how you can easily clear an emergency via client.disableEmergency(); having a client.enableEmergency(); function as well, would allow you to just as easily trigger an emergency.

[wiseman]

Good idea! It might be a little while before I have a chance to do this, do you want to give it a try?

Take a look at how the disableEmergency function is implemented, including the logic in _processNavdata.

Page 35 of the AR.Drone Developer Guide describes how to send the "emergency order"; It will be very similar to how we currently send the "disable emergency" command.