add IntersectionFinder.poly_point
proto2d: add grappy function to debug (printPoly)
collisions: Checker_MvtAsPoly4
BUGFIX : in makePoly4
OPTIM :  ignore collision ParticleParticle if any radius == 0.0
Particles: remove position3dBuff, to upgrade vector_math (without using vector_list too many change and API break)
collisions: add helper function (scanNear, findFirstIntersection)
System_Simulator extends EntitySystem (no longer IntervalEntitySystem) using regular interval should be managed at caller level (because some other System should require to run at the same time : eg follower, steering behavior,...)
collisions: fix special cases (point, segment collision) that are not correctly managed by poly_poly (SAT) detection
entity_state: API change (merge some function)
clean