Blender Git Loki

Fix: Smoke wasn't using pointcache properly.
* The cache was reset almost constantly because smoke didn't save the first frame into cache. Although not necessary for smoke, it's vital to pointcache.
* Added info message to smoke cache panel for non saved files.
* Now smoke also only updates with a framestep of 1, so that scrubbing the timeline doesn't mess up the simulation.
* Among other things fixes report #23731.