Google Earth like navigation

Hi,
I'm Julien, developer from VisioTerra,
Here is our work on the navigation, we wanted it to be more like in Google Earth so people who are used to it can get pretty much the same on GlobWeb.

We've limited our modifications to only 3 files: one for a new mouse handler class, one for a new keyboard handler class, and one for a demo or example HTML page.

I hope you'll find this interesting and maybe accept this pull request.
Thanks