option to output the mapping between full grid and irr grid

[yaoyi92]

For integrating autoGR into FHI-aims. We need a mapping from the irr grid to the full grid and also the point group symmetry operator related to the mapping.

I would suggest something like this, a KPOINTS_full file along with a symmetry_operator file including the matrices for the operator.
KPOINTS_full
x y z i_irr i_op
....
symmetry_operator
i_op xx xy xz yx yy yz zx zy zz
....