* `api.lua` create separate handler for listing registered nodes, leave the areas list clean
* `hud.lua` call second handler separately
* `api.md` extended and clarified documentaion
In other words, you can retain ownership of an area but disable and
re-enable the protection aspect at will, via the area_open chat command.
By default, nothing is any different following this commit - all
existing areas are protected, as are new ones. But you can do (for
example) "area_open 1" and if you're the owner of that area, it's
now possible for other users to interact there. "area_open 1" again to
toggle the protection back on.
Where there are sub-areas, the main owner and ALL sub-area owners at a
particulare location must have set the areas to open to disable
protection.
