As per RFC-470 I have removed the XYTransform classes from lsst.afw.geom. These classes were not being used anywhere (except unit tests).
A few classes had methods that took an XYTransform but those methods were not being called (except by test code) and are now gone. The equivalents that take an lsst.afw.geom.TransformPoint2ToPoint2 remain and are tested.
I also removed the lsst.afw.geom.Functor class, which was solely used to specify components of SeparableXYTransform, and EdgeRolloffFunctor in obs_lsstSim, which was unused.