#844062: Turned the normal drag and drop editor into a renderer plugin, made the IPE part of it. Also some fairly serious code reorganization.

visibility' permission.

Added allowed layouts to settings form for panel pages, nodes, minis.

Some major restructuring, catching up to CTools. This is very much in process, there is a huge list of things that need to happen here still, but this may be checkpoint usable to the strong-stomached.

Just need to get the delete button working and then go through all the contexts, relationships and arguments to make sure their forms are working.