make USER-DIFFRACTION input example fully consistent with output and remove additional input file

compute         XRD all xrd  1.541838 Ni 2Theta 40 80 c 2 2 2 LP 1 echo

compute         SAED all saed 0.0251  Ni Kmax 0.85 Zone 1 0 0 c 0.025 0.025 0.025  &

                dR_Ewald 0.05 echo manual

compute         SAED all saed 0.0251  Ni Kmax 0.85 &

                Zone 0 0 0 c 0.025 0.025 0.025 &

                dR_Ewald 0.01 echo manual

fix             1 all ave/histo/weight 1 1 1 40 80 200 c_XRD[1] c_XRD[2] &

                mode vector file $A.hist.xrd

variable  A string bulkNi

log		$A.log

boundary        p p p

units		metal

timestep	0.001

lattice         fcc 3.52

region          box block 0 20 0 20 0 20

create_box      1 box

create_atoms    1 box

pair_style      none

mass            * 58.71

atom_modify     sort 0 0

compute         XRD all xrd  1.541838 Ni 2Theta 40 80 c 2 2 2 LP 1 echo

compute         SAED all saed 0.0251  Ni Kmax 0.85 &

                Zone 0 0 0 c 0.025 0.025 0.025 &

                dR_Ewald 0.01 echo manual

fix             1 all ave/histo/weight 1 1 1 40 80 200 c_XRD[1] c_XRD[2] &

                mode vector file $A.hist.xrd

fix             2 all saed/vtk 1 1 1 c_SAED file $A_001.saed 

dump            1 all custom 1 $A.dump id x y z 

run             0

unfix           1

unfix           2

uncompute       XRD

uncompute       SAED