[fluxus] misc plt commits

[dave]

some more...

x multitexturing build flag - now disabled by default as it seems
problematic on nvidia cards
* added start-audio to the init script by default
* lighting initialisation fix
* camera fixes (& removed two useless matrix inverts per frame)
x scons warnings removed - a single env for installing
* mouse-over works again
* destroy clear physics primitive too
x (render-physics) for displaying helper graphics
x reset-camera works
x clear clears frame callback	

There are quite a lot of new lower level functions that are part of the
binary modules, and used by the scheme layer to provide the higher level
functions, eg

(mouse-over)

Is acually now a bit of scheme (in fluxus-input.ss) that calls a new
function in fluxus-engine:

(select x y picksize)

with the current mouse coordinates. Things like this are needed as the
underlying fluxus-engine has no direct connection to inputs like the
mouse anymore.

These functions will be documented along with all the others.

cheers,

dave