[ODE] Call to set a space's AABB.

[gl]

OK, my scene graph is quadtree based.  I may do my own collision culling in
the future, but for now I create a simple space for each quadtree node,
giving me a deep space hierarchy that matches the graph.

The problem is that any spaces/nodes that contain no objects have their
bounds set to all-zeros.  Worse, any spaces that contain only other empty
spaces (ie. most of them) also have their bounds all zero.

Worst of all, if I now add a a _static_ geom to the graph, I put it into the
world's static space to avoid collision between other statics.  Problem is
that now the space belonging to the node the geom was sorted into still
keeps its bounds at 0,0,0 (as it's never added to it).

To speed up the collison callback I currently skip spaces who's bounds are
all zero, but in this scenario that no longer works.  Worse, if I remove
this check I now have to test zillions of these 'contains only other spaces'
spaces that all overlap each other (because they're all zero), or cull them
some other way.

All of these problems could be avoided if I could preset each space's AABB
to the correct dimensions.  In fact, I would like to lock this AABB so that
it never grows or shrinks - it should never grow because I currently don't
allow node overlapping, and it certainly should never shrink, so it removes
the need for the internal AABB housekeeping altogether.

I can of course hack this in myself, but would anybody else find this
useful?  Or does anyone have another approach to this?
--
gl