Changelog

Version 2.1

Implemented world blocks. World can have an optional "worldBlock" property, an integer, defining a block ID for that world's "worldBlock." Any portal made with that block in the top two corners will link to that world.
Updated to use Bukkit builtin permissions. You must use a compatible permissions plugin to use this. Read http://forums.bukkit.org/threads/permissions-faq.25080/ for more information.
Still uses sync threads to do teleportation.

Added easier drop-and-go installation code and support.
Added true multiworld support. See worlds.yml for syntax and examples.
Added per-world custom destination world.
Added per-world custom destination world for respawns.
Added command "/nethrar tp world"; Use it as a server admin to get between worlds to set up portals for people.
Added portal destination persistence to help with more complicated world setups.

Fixed teleporting when riding a minecart so that everything happens in a thread, instead of half in a thread and half synchronously (it's not okay to be a passenger of a vehicle in another world, eh?).

Fixed "moved too fast" issue causing disconnects. Unfortunate side effect: teleports exhibit just a wee bit of lag before actually occuring once you hit a portal. Depends on the server's load at the time. This will have to wait for if/when the Bukkit team fixes the checks around that disconnect.
Riderless minecart teleportation! Hidden Netherworld logic, long-distance unassisted storage cart teleportation, possibilities abound! Supposedly will work great with Evercart.
Boats! Now you can enable your crazy multiworld water coaster. Not tested as thoroughly as it should have been, buyer beware...
Various refactoring to help prepare for Nethrar v2.0.

Added option for it to always be night in the Nether (default true).
Changed Permissions support to default to false, change to true if you want to use Permissions.
Added chunk loading prior to teleporting through portals, to help alleviate more transition issues.
Nethrar now generates a config file if one is not found.
Added some checking around where Nethrar determines which block a player has interacted with, due to people reporting a situation where a player can be "in a vehicle" but either the vehicle, or it's location, are null. This will help prevent NPEs.

Added configuration option to enable a 'peaceful' Nether, empty of Ghasts and Pig zombies.
Switched to using a more polite chunk unloading function.

Added configuration option to keep chunks loaded in a variable sized radius around portals. Set "forceLoadRadius" in config.yml to > 0 if you are having issues with falling or with chunks not loading after transitioning.
Added "NethrarMinecartTeleportEvent" which is called after a player is teleported with a minecart. Plugin devs, listen for this event if your plugin does things with minecarts, and needs to know when minecarts suddenly move or get added/deleted.

Added Permissions support for permission node "nethrar.use" - give users this permission to enable use of Nethrar.

First release, with minecarts and conservative portal linking and configurable spatial compression, etc.