[#394] moved the new collision code into a new home under `me.collision`

also made the previous API now deprecated
[#394] fixed a regression where the response object was not cleared before re-using it
[#394] fixed the text description
Merge pull request #534 from juhanapaavola/master

Viewport bounds not set with isometric map #2
[#394] added the QuadTree library and "melonized" it a bit

will start playing with it tomorrow :)
[#369] Modified the quadTree implementation a bit to allow inserting entity directly

I'm not sure though on how we should manage what should be given as
parameter when inserting "children", as we need to provide the related
bounding box (me.body) and then retreive the corresponding entity
(accessible through me.body.entity)
[#369] added a debug mode for the quadtree in the debuPanel

Similar to what has been done in the ticket #103 for the region drawing
[#369] proper quadtree initialization, only populated for now once in debug mode

note : the quadtree IS NOT being used for collision, as it still need a
bit more love before being usable !
Fixed a typo, thanks Ellison :)
[#369] quadtree starting to work (but for now only in debug mode)

- the quadtree library now call the items getBounds() function to get
their relative regions
- The quadtree is now only populated with object having a body property
(that limit it to entities)
- Update the default max depth value to match the default one in the
library

Note :
- the retrieve functions still returns much more object that I would
actually expect.
- the viewport should also be passed to initialize the quadtree and not
the whole world (learning as I go)
[#369] Only populate the quadtree once per frame, instead of when the collision.check function is called

also now uses the viewport as the visible world bound (that also fixes
the debug draw mode)
fixed the collision test example
[#518] aligned documentation with the current implementation
added a optional bounds parameter to the clear function

to allows changing the quadtree bounds on reset