Added two examples of using the VTK dump style

examples/USER/vtk/.gitignore

+dump

examples/USER/vtk/in.vtk

+# 3d Lennard-Jones melt
+
+units		lj
+atom_style	atomic
+
+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 2.5
+
+neighbor	0.3 bin
+neigh_modify	every 20 delay 0 check no
+
+fix		1 all nve
+
+shell mkdir dump
+
+dump dmpvtk all vtk 50 dump/dump*.vtk id type vx vy vz fx fy fz
+
+#dump		2 all image 25 image.*.jpg type type &
+#		axes yes 0.8 0.02 view 60 -30
+#dump_modify	2 pad 3
+
+#dump		3 all movie 25 movie.mpg type type &
+#		axes yes 0.8 0.02 view 60 -30
+#dump_modify	3 pad 3
+
+thermo		50
+run		250

examples/USER/vtk/in.vtp

+# 3d Lennard-Jones melt
+
+units		lj
+atom_style	atomic
+
+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 2.5
+
+neighbor	0.3 bin
+neigh_modify	every 20 delay 0 check no
+
+fix		1 all nve
+
+shell mkdir dump
+
+dump dmpvtk all vtk 50 dump/dump*.vtp id type vx vy vz fx fy fz
+
+#dump		2 all image 25 image.*.jpg type type &
+#		axes yes 0.8 0.02 view 60 -30
+#dump_modify	2 pad 3
+
+#dump		3 all movie 25 movie.mpg type type &
+#		axes yes 0.8 0.02 view 60 -30
+#dump_modify	3 pad 3
+
+thermo		50
+run		250