[Fluxus] commits

[Dave Griffiths]

Hi all,

I've extended the way that every-frame works, so you can add and manage
your own frame hooks. This means you can run multiple scripts at the
same time, or have things running in the background unaffected by
(clear) or (every-frame). Fluxa uses this, and some other stuff might in
the future.

You add your own with:
(add-frame-hook! id thunk)

Which adds a hook with a given id - the every-frame id is 0, so 
(every-frame (draw-cube))
is the same as doing:
(add-frame-hook 0 (lambda () (draw-cube)))

calling (clear) only clears hook 0, so you can add your own with
different id's and they'll get left around until you call:
(remove-frame-hook! id)
or
(clear-frame-hooks!)

to get rid of them all. 

I'va also added (locator-bounding-radius n) which allows you to set the
size of the locator bounding box (maybe it should be possible to set the
dimensions too....

I've also added the missile command script as an example. It shows how
to embed glsl shaders into fluxus scripts.

cheers,

dave