[Fluxus] commits

[Dave Griffiths]

Hi all,

A misc collection of seemingly random commits:

* Fixed the startup crash on OSX
* Added a pow unit generator to fluxa
* Sped up pdata-set!/pdata-ref
* Made (backfacecull) local state rather than global - in other words it
now adheres to (with-state) and can be set differently for individual
objects
* Added (hint-cull-ccw), to turn objects inside out (by setting the face
culling to remove the counter clockwise faces)

I've also partially committed a PolyPrim evaluator, which when it's
finished will calculate intersections with primitives and return pdata
values for arbitrary points on surfaces - more on this later...

A few new files, so apologies if I forgot to add something...

cheers,

dave