vectorised math:
 - A collection of fast and inline implementations of mathematical functions.
 - The functions can be used in autovectorised loops.
 - Double and single precision implementations are available.
 - No overhead present, no intrinsics used.
 - A scalar (T(T)) and array signature (void(const unsigned int,T*,T*))
   are provided.

Born and developed at CERN, it is used, among the others, by LHC
experiments and the Geant4 simulation toolkit.

Much of the VDT code is inspired by the well known Cephes mathematical
library.