Quaternion inverse is not the same as conjugate

[mbierlee]

In https://github.com/Dav1dde/gl3n/blob/a010ceac612072ee5e945be75c577af630ed0674/gl3n/linalg.d#L2097-L2108

It is stated that the inverse of a quaternion is the same as its conjugate. This is not correct. The conjugate is what it is doing now, the inverse should be conjugate / magnitude_squared.

See also: https://www.3dgep.com/understanding-quaternions/#quaternion-conjugate https://www.3dgep.com/understanding-quaternions/#quaternion-inverse