Editor: rotation

[Nico8340]

Description

This pull request improves the logic of converting from quaternion to Euler, thus eliminating previously discovered rotation issues.
Thus fixes #496

Explanation

The issue originates from the logic of the getEulerFromQuat function, which was fixed by handling euler singularities.
The function has been refactored above for easier readability.

[Fernando-A-Rocha]

Congrats 🎉!

[chris1384]

It works for the most part, but the object gets flipped at -90 on Y axis if treshold returns values near -0.5.
Probably an oversight, unsure if it's a definite fix.

    elseif treshold < -0.499 then
        return {math.deg(2 * math.atan2(q1, q0)), -90, 0}

Great job anyways!!

[Nico8340]

It works for the most part, but the object gets flipped at -90 on Y axis if treshold returns values near -0.5. Probably an oversight, unsure if it's a definite fix.

    elseif treshold < -0.499 then
        return {math.deg(2 * math.atan2(q1, q0)), -90, 0}

Great job anyways!!

It was done this way on purpose, to deal with problems caused by gimbal lock.
If you want, you can make a fork of my fork (pun intended) and test it yourself.