Got compute working for quadratic model

thermo_style	custom &

		pe            pxy            c_bsum2[20]   c_vbsum[220]    v_db_2_100 &

		c_snap[1][43] c_snap[13][43] c_snap[1][42] c_snap[12][42] c_snap[6][37] 

		c_snap[1][43] c_snap[13][43] c_snap[1][42] c_snap[12][42] c_snap[6][42] 

thermo_modify 	norm no

# dump 		mydump_db all custom 1000 dump_db id c_db[*]

    i = list->ilist[ii];

    const int itype = type[i];

    const int ielem = map[itype];

    // element map not yet implemented

    // const int ielem = map[itype];

    const int ielem = itype-1;

    const int elemoffset = nparams*ielem;

    // linear contributions