Panel anchors should ignore scale

[JoeLudwig]

Right now panel anchors are a simple transform node that assumes its parent will be 1m x 1m big and positions its children accordingly. Unfortunately that means panel children need to be under the transform for the model, so they inherit the scale transform that's above that model. This is really annoying to use because you have to know the scale of the parent panel just so you can back it out before applying whatever scale you actually want on your node, if any.

Instead AvPanelAnchor should figure out what its parent panel is and use that panel's width to compute an unscaled transform for itself. Ideally that would happen client side without adding a new node type.