Blender Git Loki

Misleading defaults for smoke flow particle system:
* Show unborn was on by default, so smoke got emitted from all particles regardless of their birth time, not a good default in my opinion.
* What made things worse was that particles weren't shown in viewport, so you didn't even know the particles were considered alive from the very first frame! (Not rendering is a good default, but they should still be visible in viewport!)