Implement rigid body transformation for head IK

[gizemozd]

For now, what we are using just considers 2D vectors. Instead, we can use this method where the rotation matrix between two surfaces is found via SVD. I have tried this on my data and the results look quite right.

For now, head kinematics is calculated correctly either way so I will implement this as an additional feature later on.
Note that this rigid body transformation can be used not only for head kinematics but also correcting fly's orientation, etc.