Box kernels implemented and tested, including transformation matrices and microkernels for Vc and Cilk backends.
Merge branch 'master' of https://git.cern.ch/reps/VecGeom
introduced interfaces for more MatrixTransformation functionality ( needed by locate points )
simple version of LocalToMaster and matrix multiplication; enough to test location of particles
Merge branch 'master' of https://git.cern.ch/kerberos/VecGeom
fix in transformation matrix (for virtual interfaces)