* identify and pair portals by type/color
* save portal pairs to disk and reload them on restarting the server
* deactivate most recently placed portal and replace with newly placed one when 3+ portals are created
* teleport from one to the other a set time after entering a teleportation chamber and closing the door
* automatically open the door after effects wear off
* close the door on the other side when someone shuts the door
* teleport everyone inside the portal, not just the person who closed the door
* interrupt teleportation if portal is destroyed mid-teleportation
* save any effects that would be overwritten by teleportation (including to disk!), and put them back when the player opens the door or arrives