cartwheel: switch to alternative swing leg controller implementation
cartwheel: eliminate PoseController class (functionality now partly
	in TorqueController and SwingController)
cartwheel: eliminate Character class and related infrastructure
cartwheel: rename AffineTransform to SE3Tr (the earlier name was
    misleading, since the class did not represent a general affine
    transform)
cartwheel: fix some include guards
kintree: first version of RNE (Recursive Newton-Euler) and CRB
    (Composite-Rigid-Body) algorithms (work in progress)