Blender Git Loki

Fix T47189: Large smoke simulation sometimes make Blender crash.

Issue was with very thin domains along one or two axes, these could lead to simulation
with only one cell width - and smoke code assumes we have at least 4 cells in each direction.

So now, we clamp resolution to a minimum of 4 in smoke_set_domain_from_derivedmesh().

Note: in extreme cases like this report, this will generate very un-cubic cells,
check it still works OK in 3DView is needed here.

Thanks to @genscher and @kevindietrich for help on this issue. :)