more balanced 16x32, 32x16 and 32x32 decisions (#276)
more balanced 16x32, 32x16 and 32x32 decisions (#276)

Reduces ringing significantly in d16 and worse.
Some reduction in d8.
Finest qualities get changes only in smooth areas that already look
great.

0.13 % improvement on BPP*pnorm
0.58 % on butteraugli distance
0.016 % size reduction

Before:

```
Compr                 Input    Compr            Compr       Compr  Decomp  Butteraugli
Method               Pixels     Size              BPP   #    MP/s    MP/s     Distance    Error p norm   PSNR   QABPP     DCT2     DCT4   DCT4X8      AFV     DCT8  DCT8X16  DCT8X32    DCT16 DCT16X32    DCT32           BPP*pnorm   Errors
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
jxl:d0.8:epf0      17972865  3952043    1.75911542205   1   2.348  13.709   1.57893729   0.52330958503  41.73   2.121 0.000000 0.000911 0.203567 0.020553 0.049902 0.230698 0.000000 0.408836 0.017035 0.068597  0.9205619615324337        0
jxl:d1:epf1        17972865  3450570    1.53590203899   1   2.565  20.029   1.94662952   0.60612205767  40.65   2.128 0.000000 0.000911 0.192140 0.020753 0.049001 0.201234 0.000000 0.396715 0.028686 0.110872  0.9309441042592400        0
jxl:d2:epf3        17972865  2246256    0.99984326372   1   2.850  16.446   3.41899276   0.95125633921  37.50   2.256 0.000000 0.001139 0.159970 0.021308 0.044515 0.151339 0.000000 0.301154 0.098338 0.223284  0.9511072428334978        0
jxl:d3:epf0        17972865  1680140    0.74785628223   1   2.758  24.550   4.57588768   1.27704026411  35.28   2.324 0.000000 0.001139 0.134923 0.020033 0.041385 0.134367 0.000000 0.233724 0.175026 0.261970  0.9550425841796468        0
jxl:d4:epf3        17972865  1390103    0.61875633072   1   2.409  14.737   5.85040092   1.56284952646  34.11   2.425 0.000000 0.001139 0.111054 0.018039 0.034800 0.120786 0.000000 0.200152 0.228554 0.289147  0.9670230384675962        0
jxl:d8:epf1        17972865   813211    0.36197278508   1   2.823  24.289   9.37444782   2.51584719998  30.89   2.406 0.000000 0.001367 0.058484 0.011665 0.018783 0.088738 0.000000 0.132865 0.326921 0.367145  0.9106682178227494        0
jxl:d16:epf3       17972865   475322    0.21157316877   1   2.872  14.535  21.55422401   4.42386021454  28.62   2.641 0.000000 0.001367 0.016729 0.003927 0.003998 0.049290 0.000000 0.072942 0.332077 0.527130  0.9359701238049873        0
jxl:d24:epf3       17972865   358029    0.15936424159   1   2.590  14.324  21.47615433   5.77418376695  27.34   2.649 0.000000 0.001367 0.007673 0.001791 0.001741 0.033907 0.000000 0.051647 0.293705 0.616068  0.9201984168450851        0
jxl:d32:epf3       17972865   292046    0.12999418846   1   2.847  13.934  25.84580421   7.02234695199  26.51   2.668 0.000000 0.016636 0.003781 0.000897 0.000957 0.026137 0.000000 0.036677 0.250632 0.672359  0.9128642931176300        0
Aggregate:         17972865  1125217    0.50085125627 ---   2.667  16.944   6.81123365   1.86408749564  33.21   2.393 0.000000 0.001552 0.051750 0.008541 0.013921 0.091328 0.000000 0.151461 0.135466 0.279207  0.9336305639835538        0
```

After:

```
Compr                 Input    Compr            Compr       Compr  Decomp  Butteraugli
Method               Pixels     Size              BPP   #    MP/s    MP/s     Distance    Error p norm   PSNR   QABPP     DCT2     DCT4   DCT4X8      AFV     DCT8  DCT8X16  DCT8X32    DCT16 DCT16X32    DCT32           BPP*pnorm   Errors
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
jxl:d0.8:epf0      17972865  3951942    1.75907046539   1   2.324  13.807   1.57893729   0.52331089591  41.73   2.121 0.000000 0.000911 0.203567 0.020553 0.049902 0.230626 0.000000 0.408822 0.017234 0.068483  0.9205407412221729        0
jxl:d1:epf1        17972865  3450706    1.53596257469   1   2.538  20.125   1.94662952   0.60610525355  40.65   2.128 0.000000 0.000911 0.192140 0.020753 0.049001 0.201177 0.000000 0.396829 0.029199 0.110303  0.9309549857768020        0
jxl:d2:epf3        17972865  2246506    0.99995454258   1   2.826  16.524   3.41899276   0.95121670445  37.50   2.246 0.000000 0.001139 0.159978 0.021315 0.044529 0.151353 0.000000 0.301396 0.104035 0.217301  0.9511734645939139        0
jxl:d3:epf0        17972865  1679780    0.74769604067   1   2.780  24.514   4.76437998   1.27694160442  35.28   2.321 0.000000 0.001139 0.135008 0.020033 0.041445 0.134325 0.000000 0.233283 0.181521 0.255816  0.9547641817919317        0
jxl:d4:epf3        17972865  1390051    0.61873318472   1   2.398  14.544   5.85040092   1.56297457360  34.10   2.430 0.000000 0.001139 0.110922 0.018061 0.034779 0.120629 0.000000 0.198984 0.239920 0.279233  0.9670642355616933        0
jxl:d8:epf1        17972865   811812    0.36135006856   1   2.788  23.422   9.37444782   2.51424949430  30.89   2.407 0.000000 0.001367 0.058295 0.011626 0.018769 0.088538 0.000000 0.128891 0.354582 0.343899  0.9085242271468007        0
jxl:d16:epf3       17972865   475248    0.21154023023   1   2.836  13.781  19.64723206   4.41670512959  28.63   2.675 0.000000 0.001367 0.016718 0.003920 0.004023 0.048898 0.000000 0.067344 0.381702 0.483488  0.9343108199727461        0
jxl:d24:epf3       17972865   358126    0.15940741779   1   2.588  13.989  21.47615433   5.75762783145  27.36   2.626 0.000000 0.001367 0.007627 0.001805 0.001705 0.033558 0.000000 0.045195 0.354981 0.561657  0.9178085852275816        0
jxl:d32:epf3       17972865   292118    0.13002623677   1   2.796  14.169  25.83151817   6.98935655673  26.53   2.639 0.000000 0.016636 0.003810 0.000904 0.000961 0.026058 0.000000 0.031706 0.315754 0.612251  0.9087997305448716        0
Aggregate:         17972865  1125031    0.50076852951 ---   2.646  16.767   6.77137520   1.86203845214  33.21   2.391 0.000000 0.001552 0.051733 0.008552 0.013905 0.091067 0.000000 0.144941 0.148250 0.266164  0.9324502575761613        0
```
libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl