Convert quaternions to Euler angles. Note that the Euler angles are different for different rotation sequence. The Euler angles rotation sequence used in this code is z-y'-x'' (yaw, pitch, roll). The rotation is intrinsic, i.e., rotates along new axes. This definition is widely used by aerospace engineers.

Reference: https://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles

Verification: www.andre-gaschler.com/rotationconverter/
Note that quaternions to Euler is not unique but Euler to quaternions is unique. So it is better to get the Euler of a normalized quaternions (such as [ 0.7071068, 0, 0.7071068, 0]) from the function and use the verification tool to convert the Euler to quaternions. The quaternions should match if the rotation sequence is correctly chosen.