Fix: Node Solo Can No Longer Accidently Nuke Previous Visibility Settings
(Node Solo == Shift + Click on visibility icon...)
Previous Behavior: Shift clicking on a layer's visibility icon to 'solo'
it and then left clicking on another layer's visibility would completely
nuke previous visibility settings. This was very destructive!
New Behavior: If there's a solo active on any given node, a single left
click on any visibility icon will simply restore the original visibility
status for all nodes. This means that you will no longer break
visibility of your document.