add some simple tests for displace_atoms

test/02_commands/in.displace_atoms-000

@@ -0,0 +1,22 @@
+
+timer off
+lattice		fcc 0.8442
+region		box block 0 10 0 10 0 10
+create_box	1 box
+create_atoms	1 box
+mass		1 1.0
+
+velocity	all create 3.0 87287
+
+pair_style	lj/cut 2.5
+pair_coeff	1 1 1.0 1.0
+
+neighbor	0.3 bin
+neigh_modify	every 20 delay 0 check no
+
+displace_atoms  all move 0.0 0.0 0.0
+
+fix		1 all nve
+
+thermo		50
+run		200

test/02_commands/in.displace_atoms-001

@@ -0,0 +1,22 @@
+
+timer off
+lattice		fcc 0.8442
+region		box block 0 10 0 10 0 10
+create_box	1 box
+create_atoms	1 box
+mass		1 1.0
+
+velocity	all create 3.0 87287
+
+pair_style	lj/cut 2.5
+pair_coeff	1 1 1.0 1.0
+
+neighbor	0.3 bin
+neigh_modify	every 20 delay 0 check no
+
+displace_atoms  all move 0.01 -0.01 0.01
+
+fix		1 all nve
+
+thermo		50
+run		200

test/02_commands/in.displace_atoms-002

@@ -0,0 +1,26 @@
+
+timer off
+lattice		fcc 0.8442
+region		box block 0 10 0 10 0 10
+create_box	1 box
+create_atoms	1 box
+mass		1 1.0
+
+velocity	all create 3.0 87287
+
+pair_style	lj/cut 2.5
+pair_coeff	1 1 1.0 1.0
+
+neighbor	0.3 bin
+neigh_modify	every 20 delay 0 check no
+
+variable        randx atom random(0.0,0.01,1111)
+variable        randy atom random(0.0,0.01,1111)
+variable        randz atom random(0.0,0.01,1111)
+
+displace_atoms  all move v_randx v_randy v_randz
+
+fix		1 all nve
+
+thermo		50
+run		200