@ADD: Vlad Popovici's lti::rotation functor has been added to the library. It uses the "Rotation by Shear" algorithm which is some times slightly faster than the lti::geometricTransform. In general, the current algorithm is slower in the debug version, and in the release is always faster rotating angles around 45, 135, -135 and -45 degrees, and much much faster for rotations of exactly k*90 degrees. For the angles around k*90, the lti::geometricTransform using bilinear interpolation is still faster, and using the kNearestNeighbor interpolation even faster than the new one. The algorithm may change in the future to increase efficiency.