New IsoWorld system to test the rendering system.

- Added a new Box3 -> Box3Sized
- Bug correction in Mouse Wheel.
- Bug correction in Mouse Drag, when going out of the window.
- Library : renamed getOrAdd into addAndGet
- Library : added getOrAdd with a code block to generate the Resource.
- Added a Zoom avatar event (maps to scroll wheel or pinch gestures).
- Added a way to pass initialization code in Renderer.start() to avoir
thread problems.
- Added a mesh.draw(gl) method in Mesh to avoid using the last vertex
array, shortcut to mesh.lastva.draw(mesh.drawAs(gl)).