Merge pull request #2 from brandonw/master

Update to latest rust
Update to the last nalgebra api.
Add bounding sphere computation.
Start the addition of bezier surfaces and curves.

Collision detection is not yet implemented for anything but `BezierSurface` vs. `Ball`.
Ray-casting is not implemented (it always returns `None` for now).

This also adds a new utility (needed for bezier curve/surface subdivision): `VecSlice/VecSliceMut`.
It is a wapper on `Vec` that give access on regularly-spaced elements using natural, continuous
indexing.
Add a cached subdivision tree to speed up the ball-vs-bezier collision detection.

However, it is not activated yet.
Also, this updates ncollide to the rust-nightly:
0.11.0-pre-nightly (faa7ba7 2014-05-31 01:06:40 -0700)