Be able to mark a portlist as uncopyable

[erkyrath]

Or maybe have a copying access level, which can be set to "never".

I used to think this was unnecessary -- the world's copyable flag was sufficient. I've changed my mind. One can imagine puzzle situations where some of the world is copyable (say, the entry area) but specific areas are restricted to puzzle solutions.

Be sure to test ordinary portlists, focussed portlists, publicly editable portlists.

[erkyrath]

(External portals are inherently copyable. Test that case anyway, to make sure it doesn't break, but we don't expect to block copying in that case.)

[erkyrath]

The workaround for the moment is to have two worlds, copyable and not, which pretend to be the same world.