SpatialQuickSortCollider is nice, because it's only 70 lines long. But has one bug.

SpatialQuickSortCollider is nice, because it's only 70 lines long. So it's useful for learning yade.

But it didn't respect groupMask. So here I am fixing this problem :)

I am extracting stuff from my quantum mechanics branch that is not quantum related. spatial collider is enough for quantum wavefunctions. But groupmasks need to be working :)

Now you can run any of the examples after replacing InsertionSortCollider with SpatialQuickSortCollider. And they will work, slower. I am not sure if we need any extra tests for this simple case? In fact this is tested indirectly in the incoming quantum mechanics tests :)