Merge particle stuff from liquidfun back into mainline

```
Not sure whether this is an option, but I at least wanted to give it a try. It 
would be quite awesome if some of the changes from liquidfun 
(http://google.github.io/liquidfun/) could be merged upstream.
```

Original issue reported on code.google.com by `Martin.G...@gmail.com` on 11 May 2015 at 7:29
