A plugin type provides functionality for finders. This means we can vary for events/directories/etc.
You select the finder type plugin in the node type form, to enable a node type as being either for channels or entries for a finder type.
The finder type of a node type gets stored in the node type's third party settings
The plugin will be responsible for creating fields, updating config, etc etc.
I'm experimenting with using bundle fields instead of config fields. Currently there's one bundle field in the base plugin -- please try to break this!!!
If we go with the bundle field approach, then there will be a 'Directories Legacy' plugin to keep doing config fields for sites built with Directories 3.
WIP.
Commits have got progressively messier.
The current plan is: