Add a tuning tab to the cfclient

[knmcguire]

So for tuning the kalman filter and controller, it would be handy to have some kind of sliding mechanism where these variables can be changed while the crazyflie is in flight, so that the user can see what these changes have as an effect on the behavior. This would be handy for tuning the PID controller if somebody mounted something heavy on it, or to tune the Kalman filter error models.

[knmcguire]

related also to the tuning script here: bitcraze/crazyflie-lib-python#146. I think it would be better to actually have a cfclient tab instead of a seperate cflib script

[jonasdn]

The tab should leverage the new persistent parameters. The "scope" goal would be that the tuning tab should include everything needed to tune a completed custom Crazyflie Bolt kit.

[knmcguire]

Done in PR #614