Re: [ opende-Patches-1335198 ] Sweep and Prune Space

Okay, I've added this new Sweep and Prune space. I had to do some
additional work to get it though:

* The space doesn't store geoms as a usual linked list, so a custom
destructor was required to remove / destroy geoms under it's
ownership.

* Each call to collide caused a memory allocation, I've changed that
to use a scratch pad mechanism so allocations are only performed when
the geom count changes. Now I think of it there is probably room for
improvement here by replacing my code with a dArray.

* The code had a dependency on the radix sorter from OPCODE. To break
this I've copied the inner workings into the SAP source file - it
doesn't amount to very much when you boil off the fluff.

* The was the radix sorter was used before would leak, now it uses a
very simple reference counter to catch this.

Here a few other notes:

* The radix sorter uses IEEE floats, so AABBs are actually cast if
you're building in double precision mode. I'm hopeful that this isn't
a problem - if it is there are other spaces you could use for now.

* I changed demo_crash to use this new space.

Finally, I've not profiled this at all - I'm hoping Mark Williams,
etc. can tell me if it's even faster now I've incorporated it
properly.

Regards,
David Walters