replace variable length arrays in fix rx of USER-DPD with new/delete

      error->all(FLERR,"fix rx cannot be combined with fix property/atom");

  char **tmpspecies = new char*[maxspecies];

  int tmpmaxstrlen = 0;

  for(int jj=0; jj < maxspecies; jj++)

    tmpspecies[jj] = NULL;

          error->all(FLERR,"Exceeded the maximum number of species permitted in fix rx.");

        tmpspecies[nUniqueSpecies] = new char[strlen(word)+1];

        strcpy(tmpspecies[nUniqueSpecies],word);

        tmpmaxstrlen = MAX(tmpmaxstrlen,strlen(word));

        nUniqueSpecies++;

      }

      word = strtok(NULL, " \t\n\r\f");

  newarg2[0] = id_fix_species_old;

  newarg2[1] = group->names[igroup];

  newarg2[2] = (char *) "property/atom";

  char *str1 = new char[tmpmaxstrlen+3];

  char *str2 = new char[tmpmaxstrlen+6];

  for(int ii=0; ii<nspecies; ii++){

    char str1[2+strlen(tmpspecies[ii])+1];

    char str2[2+strlen(tmpspecies[ii])+4];

    strcpy(str1,"d_");

    strcpy(str2,"d_");

    strncat(str1,tmpspecies[ii],strlen(tmpspecies[ii]));

    strcpy(newarg[ii+3],str1);

    strcpy(newarg2[ii+3],str2);

  }

  delete[] str1;

  delete[] str2;

  newarg[nspecies+3] = (char *) "ghost";

  newarg[nspecies+4] = (char *) "yes";

  newarg2[nspecies+3] = (char *) "ghost";