Sandbox3D v.0.0.0.3 -- Trackball support

I just posted a new version of Sandbox3D.  I a dded trackball support for the rotation values, so that you can hold down the right mouse button and move the mouse around to rotate the mesh.  What is cool is that I wired up the IPropertyChange interface to the data object so that the sliders would dynamically update when the trackball moves.  Two way databinding...yeah!Note: The trackball class also supports scaling via the mousewheel, but I remmed out the code and haven't wired it up yet.