lima/vecgeom-234-v2 - Implement a templated Tiny<> struct to avoid divide-by-zero exceptions

I have followed the e-mail suggestions by Philippe and Andrei, to implement a template-based Tiny<> structure and two functions NonZero(x) and NonZeroAbs(x), to make sure Tiny<> gets added to x or Abs(x) thus avoiding divide-by-zero exception.

Box unitary test now has floating point exceptions enabled, to make sure that the divide-by-zero cases are properly avoided.