Prototype 1.6 compatible :)

The new branch for prototype 1.6 is now ok and runs Slidy smoothly, which is a good test application !

I think the patch will be integrated for the 0.9.0 but we still have to do some work for 0.8.0 release before :)

After the 0.9.0 release, I may maintain a Prototype 1.5 compatible version, thanks to Mercurial :D

P.S.: I've mis-pushed the prototype 1.6 patch on the current official tip... will remove it ASAP !