dot
Calculates the dot product (scalar product) of two quaternions, a and b.
The dot product is computed as the sum of the products of their corresponding components (a.x*b.x + a.y*b.y + a.z*b.z + a.w*b.w).
For two unit quaternions, their dot product is equal to cos(angle/2), where angle is the angle of rotation that transforms the orientation represented by one quaternion to that of the other. It provides a measure of similarity between the two rotations.
Return
The dot product of the two quaternions as a Float scalar value.