Resolve Camera's and Quaternion's EulerAngle usages

[Kejoko]

The camera and quaternion class have somewhat duplicate logic, which each yield a different result. To make things weirder, the camera class's EulerAngle conversion functions do not work in round trip

This will likely involve some research and a genuine understanding of Euler angles and quaternions and rotations. Time to get learnt

• Ensure quaternion Euler angle logic works round trip with look directions
• Ensure camera Euler angle logic works round trip with look directions
• Use the same logic for both the camera and quaternion classes