CoR: add support for "Vo" method
Some tests seem to indicate that Vo's method described in [1] works quite well - even for the notoriously-hard series of "BM05 mouse brains scans".
It would be a nice addition in our CoR-estimators collection.
[1] Nghia T. Vo, Michael Drakopoulos, Robert C. Atwood, and Christina Reinhard, "Reliable method for calculating the center of rotation in parallel-beam tomography," Opt. Express 22, 19078-19086 (2014)