Blender Git Loki

Increase tolerance value used for copying a dense array to a sparse
grid.

This doesn't affect low resolution grids much but makes a real
difference for high res grids, as it only considers values real close to
the actual smoke or fire.

Although it might be a bit high of a value, it gives some nice file
sizes going from 106.6 Mb down to 37.7 Mb (pointcache: 264.3 Mb) in a
simple simulation with a base res of 128 and a high res of 2.