add harmonic/cut to python example folder. small tweaks to docs and examples

examples/python/in.pair_python_harmonic

@@ -0,0 +1,84 @@
+# 3d soft repulsive particles
+
+units           real
+atom_style      atomic
+
+lattice         fcc 5.0 origin 0.1 0.1 0.1
+region          box block -5 5 -5 5 -5 5
+create_box      2 box
+create_atoms    1 box
+set type 1 type/ratio 2 0.5 424662346
+mass            * 1.0
+
+velocity        all create 3.0 87287
+
+pair_style      python 9.0
+pair_coeff      * * py_pot.Harmonic A B
+
+neighbor        1.0 bin
+neigh_modify    every 2 delay 4 check yes
+
+fix             1 all nve
+
+thermo          50
+run             250 post no
+
+write_restart   repulsive.restart
+
+clear
+
+read_restart    repulsive.restart
+
+pair_style      python 10.0
+pair_coeff      * * py_pot.Harmonic A B
+
+shell rm -f python.dat
+pair_write 1 1 1000 rsq 0.1 10.0 python.dat PYTH_A_A
+pair_write 2 2 1000 rsq 0.1 10.0 python.dat PYTH_B_B
+pair_write 1 2 1000 rsq 0.1 10.0 python.dat PYTH_A_B
+
+fix             1 all nve
+
+thermo          50
+run             250 post no
+
+clear
+
+read_restart    repulsive.restart
+
+pair_style      harmonic/cut
+pair_coeff      1 1 0.2 9.0
+pair_coeff      2 2 0.4 9.0
+
+shell rm -f harmonic.dat
+pair_write 1 1 1000 rsq 0.1 10.0 harmonic.dat HARM_1_1
+pair_write 2 2 1000 rsq 0.1 10.0 harmonic.dat HARM_2_2
+pair_write 1 2 1000 rsq 0.1 10.0 harmonic.dat HARM_1_2
+
+neighbor        1.0 bin
+neigh_modify    every 2 delay 4 check yes
+
+fix             1 all nve
+
+thermo          50
+run             250 post no
+
+clear
+
+read_restart    repulsive.restart
+
+pair_style      table spline 1000
+pair_coeff      1 1 python.dat PYTH_A_A
+pair_coeff      1 2 python.dat PYTH_A_B
+pair_coeff      2 2 python.dat PYTH_B_B
+
+neighbor        1.0 bin
+neigh_modify    every 2 delay 4 check yes
+
+fix             1 all nve
+
+thermo          50
+run             250 post no
+
+# remove temporary files
+shell rm repulsive.restart harmonic.dat python.dat