Initial commit of Guldoman's pocket design, to replace locked views.

The problem as it stands is that to add views, plugins need to basically split off their own nodes. This isn't sustainable, because if you have a ton of plugins they're going to start stepping on each other, and unless they're specifically coded around each other, it devolves into chaos.

Enter, the pocket system. Where you can simply tell RootView to add your view to a specific pocket, and have the central system worry about exactly how to lay it out, and where. It's configurable by the user in config, and in theory should allow many plugins to play nicely with each other.

The PR currently works for all the defaults (and saves us some SLOC); but I'm going to be testing this going forward on my IDE plugins, to see how easy it is to get them to all play nice. Will report back on this.