Changes
/* PIDs */
==== PIDs ====
* PID by MrSteele:
** Explained (Part 1): https://www.youtube.com/watch?v=FZ5GFjmD9f0
** Tuning (Part 2): https://www.youtube.com/watch?v=7ZSZBZ4s-28
* PID explained by RCModelReviews: https://www.youtube.com/watch?v=0vqWyramGy8
* PID tuning (by IBCrazy): https://www.youtube.com/watch?v=5VXMXwzlNLU
* PID tuning 101 http://iflyquad.com/2016/03/11/the-pid-tuning-guide-short-version/
