Added test file

Author: rozyczko

src/diffpy/structure/tests/testdata/Ni_ref.cif

@@ -0,0 +1,21 @@
+data_2102245
+_cell_length_a 3.562
+_cell_length_b 3.562
+_cell_length_c 3.562
+_cell_angle_alpha 90.00000000
+_cell_angle_beta 90.00000000
+_cell_angle_gamma 90.00000000
+_space_group_name_H-M_ref 'F m -3 m'
+
+
+loop_
+_atom_site_label
+_atom_site_type_symbol
+_atom_site_fract_x
+_atom_site_fract_y
+_atom_site_fract_z
+_atom_site_occupancy
+_atom_site_adp_type
+_atom_site_U_iso_or_equiv
+Ni Ni 0.00000000 0.00000000 0.00000000 1.00000000 Uiso 0.025
+