WIP touch on GUI
More work on RayPicking (the scene need to be sorted). All objects use now the global object Application to get ContentManager and GraphicsDevice (not everywhere). Colliders are initialized to zero and is update by a renderable component if it exists (otherwise, it must be updated manually).
Using native BoudingSphere.CreateMerged to generate the finale boundingSphere of a model.
Colliders: compute Min/Max
Some changes on colliders + docs for colliders, renderable components and controllers.
More works on colliders
Better boundingbox but not yet really good.
Added a boudingbox renderer
Added collider.IsPickable and collider.IsTrigger
WIP : Multi texture on terrain and Weightmap generation.
Implementation of terrain multi-texturing + GUI.DrawTexture.
Implementation of a technique for updating the prepass method of a material once. Lights and cameras related stuff need to be set just one time during the update process, not in every materials instances
Added tiling/offset on all shaders and materials + fixed last commit (material/shader matching).
Added a GUISkin sample.
ReflectiveMaterial: Reflection map + diffuse texture.
WaterMaterial: Reflective map + water texture + better normal perturbations.