Fixes several bugs in fix wall/gran, wall/gran/region:

# pour cohesive particles on flat wall, let them flow

log		pour_wall_granular.log

atom_style	sphere

units		lj

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# Geometry-related parameters

###############################################

variable	boxx equal 50

variable	boxy equal 50

variable	boxz equal 20

variable	xc equal 0.5*${boxx}

variable	yc equal 0.5*${boxy}

###############################################

# Particle-related parameters

###############################################

variable	rlo equal 0.25

variable	rhi equal 0.5

variable	dlo equal 2.0*${rlo}

variable	dhi equal 2.0*${rhi}

variable	dens equal 1.0

variable skin equal 0.3*${rhi}

#############

region 		boxreg block 0 ${boxx} 0 ${boxy} 0 ${boxz}

create_box	2 boxreg

change_box	all boundary p p f

comm_modify 	vel yes

region		insreg cylinder z ${xc} ${yc} 5 15 ${boxz}

fix		1 all nve/sphere

fix		grav all gravity 10 vector 0 0 -1

fix		ins1 all pour 1000 1 3123 region insreg diam range ${dlo} ${dhi} dens ${dens} ${dens}

fix		ins2 all pour 1000 2 3123 region insreg diam range ${dlo} ${dhi} dens ${dens} ${dens}

comm_modify	vel yes

neighbor	${skin} bin

neigh_modify	delay 0 every 1 check yes

#pair_style	gran/hertz/history 1e5 1e5 1e3 1e3 0.5 1

#pair_coeff	* *

pair_style	granular 

pair_coeff	1 * hertz/material 1e5 1e3 0.3 tangential mindlin NULL 1.0 0.5

#pair_coeff	2 2 jkr 1e5 1e4 0.3 50 tangential mindlin NULL 1.0 0.5 rolling sds 1e3 1e3 0.1 twisting marshall

pair_coeff	2 2 jkr 1e5 0.1 0.3 50 tangential mindlin NULL 1.0 0.5 rolling sds 1e3 1e3 0.1 twisting marshall damping tsuji

#pair_coeff	* * hertz/material 1e5 1e3 0.3 tangential mindlin NULL 1.0 0.5

#fix		3 all wall/gran granular hertz/material 1e5 1e4 0.3 tangential mindlin 1e5 1.0 0.5 rolling sds 1e3 1e3 0.1 twisting marshall zplane 0 NULL 

fix		3 all wall/gran granular hertz/material 1e5 0.5 0.3 tangential mindlin 1e5 1.0 0.5 damping tsuji zplane 0 NULL 

thermo_style	custom step cpu atoms ke

thermo_modify	lost warn

thermo		100

timestep	0.001

dump		1 all custom 100 pour_wall_granular.dump id type radius mass x y z 

run		150000

    iarg = 4;

    damping_model = VISCOELASTIC;

    roll_model = twist_model = NONE;

    tangential_history = roll_history = twist_history = 0;

    while (iarg < narg) {

      if (strcmp(arg[iarg], "hooke") == 0) {

        if (iarg + 2 >= narg)

                         "stiffness requires a normal contact model "

                         "that specifies material properties");

            }

            tangential_coeffs[0] = 4*(2-poiss)*(1+poiss)/Emod;

            tangential_coeffs[0] = Emod/4*(2-poiss)*(1+poiss);

          } else {

            tangential_coeffs[0] = force->numeric(FLERR,arg[iarg+2]); //kt

          }

                           double *contact)

{

  double fx,fy,fz,nx,ny,nz;

  double radsum,r,rinv;

  double r,rinv;

  double Reff, delta, dR, dR2;

  double vr1,vr2,vr3,vnnr,vn1,vn2,vn3,vt1,vt2,vt3;

  double shrmag,rsht;

  r = sqrt(rsq);

  radsum = rwall + radius;

  E = normal_coeffs[0];

  radsum = radius + rwall;

  if (rwall == 0) Reff = radius;

  else Reff = radius*rwall/(radius+rwall);

  vn2 = ny*vnnr;

  vn3 = nz*vnnr;

  delta = radsum - r;

  delta = radius - r;

  dR = delta*Reff;

  if (normal_model == JKR) {

    history[0] = 1.0;