lib: intro the geometry module

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib/geometry: use left and right points in lines

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib/geometry: more inits for Box and Box3d

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib/geometry: add intersects and contains methods to ABoxed

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>