Quaternion.slerp

void slerp(graphene.quaternion.Quaternion b, float factor, out graphene.quaternion.Quaternion res) nothrow

Interpolates between the two given quaternions using a spherical linear interpolation, or SLERP, using the given interpolation factor.

`b`	a #graphene_quaternion_t
`factor`	the linear interpolation factor
`res`	return location for the interpolated quaternion