"Smoke and Dust" rendering does not always work

[JayFoxRox]

The effect can be seen on the second screenshot in #97. However, I can't seem to make it work anymore.
The effect simply doesn't render for me. Both, the engine smoke and the splash (Dust / Snow / Sand / ..) effects are missing regardless of the menu setting.

I believe I also had a regression with the known issue where "Smoke and Dust" rendering and "Lensflares" video settings keep turning themselves themselves off (which I was unable to reproduce later). However, I also had video configurations which caused this problem (effects not shown) when the options were still enabled in the menu.

We should do regression testing first, starting with the version from #97.