progress in basloc

modification in module rays.py 

+ It remains to check if normal inversion is required
+ handling n.si = 1 -- cross product undefined
+ diffaction 
+ Bi and Bo are unitary det M = +/- 1

make use of the powerfull multidimensional cross product 
np.cross(v1,v2,axisa=0,axisb=0,axisc=0)