Replacing the monolithic and crude "if...else if...else if..." command handler in WBCommand.java with every command crammed in there, each command is now handled in a separate subclass in the new "com.wimbli.WorldBorder.cmd" package. This is inspired by the way the Factions plugin handles subclassed commands.
This is the first pass of the command handling rework. I still need to do some further testing, and I plan to further improve feedback for input errors to also show some basic help info along with the command examples.
/wb [world] set <radiusX> [radiusZ] spawn - uses the world's spawn point.
/wb set <radiusX> [radiusZ] player <name> - centers a border on the specified player.
Working around Minecraft and Bukkit client/server glitches when teleporting an entity which has a passenger or is a passenger is the whole reason for this "feature". The need was introduced a few Minecraft versions back when this well and truly broke; hopefully they will fix the underlying problems eventually.