snapshot: don't try to compress too much
snapshot: don't try to compress too much

Compression takes a looot of memory (normal).
With maximum compression, we took over 750 MiB...
Now, with minimem compression, we just lose a couple of
hundreds of bytes per snapshot, but we are back to a much
more decent memory consumption.

war2/war2edit,jeanguyomarch/war2edit,war2/war2edit,war2/war2edit,jeanguyomarch/war2edit,jeanguyomarch/war2edit