implement the `scale` keyword of `fix adapt` for diameter and charge

void FixAdapt::post_constructor()

{

  if (!resetflag) return;

  // Create local Fix Store even when ressetflag == false, to be able to use `scale` keyword for charge and diameter

  if (!diamflag && !chgflag) return;

  // new id = fix-ID + FIX_STORE_ATTRIBUTE

  newarg[4] = (char *) "1";

  newarg[5] = (char *) "1";

  if (diamflag) {

  if (diamflag && atom->radius_flag) {// Previously unsafe! The radius_flag was not checked, could run an atom_style w/o radius attribute and get here without a previous check / error !

    int n = strlen(id) + strlen("_FIX_STORE_DIAM") + 1;

    id_fix_diam = new char[n];

    strcpy(id_fix_diam,id);

    }

  }

  if (chgflag) {

  if (chgflag && atom->q_flag) {// Previously unsafe! The q_flag was not checked, could run an atom_style w/o charge attribute and get here without a previous check / error !

    int n = strlen(id) + strlen("_FIX_STORE_CHG") + 1;

    id_fix_chg = new char[n];

    strcpy(id_fix_chg,id);

  }

  // fixes that store initial per-atom values

  /* Unnecessary ? `fix_diam` and `fix_chg` seem to be already defined in FixAdapt::post_constructor(), commenting them out does not crash my MWE

  if (id_fix_diam) {

    int ifix = modify->find_fix(id_fix_diam);

    if (ifix < 0) error->all(FLERR,"Could not find fix adapt storage fix ID");

    int ifix = modify->find_fix(id_fix_chg);

    if (ifix < 0) error->all(FLERR,"Could not find fix adapt storage fix ID");

    fix_chg = (FixStore *) modify->fix[ifix];

  }

  }*/

  if (strstr(update->integrate_style,"respa"))

    nlevels_respa = ((Respa *) update->integrate)->nlevels;

      // also scale rmass to new value

      if (ad->aparam == DIAMETER) {

        int mflag = 0;

        if (atom->rmass_flag) mflag = 1;

				/* `mflag` unnecessary ? the test if (!atom->radius_flag) in FixAdapt::init() should perevent `atom->rmass_flag == false`. Unless there can be combinations of atoms with `radius` but without `rmass`

				It could also be unsafe since rmass_flag could be added using `fix property/atom` even for an atom_style that does not have radius attributes */

        double density;

        double *vec = fix_diam->vstore; // Get initial radius to use `scale` keyword

				double *radius = atom->radius;

        double *rmass = atom->rmass;

        int *mask = atom->mask;

        int nlocal = atom->nlocal;

        int nall = nlocal + atom->nghost;

        if (mflag == 0) {

          for (i = 0; i < nall; i++)

            if (mask[i] & groupbit)

              radius[i] = 0.5*value;

        } else {

        for (i = 0; i < nall; i++)

          if (mask[i] & groupbit) {

						density = rmass[i] / (4.0*MY_PI/3.0 *

                                  radius[i]*radius[i]*radius[i]);

              radius[i] = 0.5*value;

						if (scaleflag) radius[i] = value * vec[i];

						else radius[i] = 0.5*value;

            rmass[i] = 4.0*MY_PI/3.0 *

              radius[i]*radius[i]*radius[i] * density;

          }

        }

      } else if (ad->aparam == CHARGE) {

        double *vec = fix_chg->vstore; // Get initial charge to use `scale` keyword

				double *q = atom->q;

        int *mask = atom->mask;

        int nlocal = atom->nlocal;

        int nall = nlocal + atom->nghost;

        for (i = 0; i < nall; i++)

          if (mask[i] & groupbit) q[i] = value;

          if (mask[i] & groupbit) {

						if (scaleflag) q[i] = value * vec[i];

						else q[i] = value;

					}

      }

    }

  }

  modify->addstep_compute(update->ntimestep + nevery);

  // re-initialize pair styles if any PAIR settings were changed

  // ditto for bond styles if any BOND setitings were changes

  // ditto for bond styles if any BOND settings were changed

  // this resets other coeffs that may depend on changed values,

  //   and also offset and tail corrections