[Fluxus] fluxus augmented reality module

[gabor papp]

hi,

i committed an initial version of the fluxus-artkp module to git, which 
is based on the artoolkitplus library 
(http://studierstube.icg.tu-graz.ac.at/handheld_ar/artoolkitplus.php) 
and provides simple ar marker detection.

demo screenshot:
http://www.flickr.com/photos/gaborpapp/4139246982/

at the moment the module only works with simple id based markers. i 
included one of them in the addons/artkp/example/data folder. it has to 
be printed in 80x80mm size. you can find all 512 markers in the 
artoolkitplus distribution in the 
ARToolKitPlus/id-markers/simple/std-border folder.

example:
addons/artkp/example/simple.scm

new functions:

(require fluxus-016/fluxus-artkp)
requires the ar module.

(ar-init (camera-width cam) (camera-height cam) "data/camera_para.dat")
initializes the ar system with the camera resolution and the camera 
parameter file/

(ar-set-threshold value)
sets the threshold value that is used for black/white conversion.

(ar-get-threshold)
returns the current threshold value.

(ar-auto-threshold #t)
enables automatic threshold calculation to adapt to changing lighting 
conditions.

(ar-get-projection-matrix)
returns the projection matrix acquired from the camera parameter file.

(define marker-count (ar-detect (camera-imgptr cam)))
processes the camera image and returns the number of markers found.

(ar-get-modelview-matrix i)
returns the modelview matrix for the marker with index i.

(ar-get-id i)
returns the id of the marker for marker index i.

(ar-get-confidence i)
returns the confidence value of the marker with index i.

comments and suggestions are welcome.

best,
gabor