New command: /wb help [command] - get help on command usage. This provides further help for any specified command. Accordingly, help info has been added to every command. This info is also provided if there was an error with the command parameters passed to any given command.

Some further changes as well, including some minor code design improvement. As part of that, the root plugin's GetWorldBorder(String worldName) method has been deprecated and replaced with proper first-letter capitalization: getWorldBorder(String worldName).

All commands have now been tested in-game and through console, and a couple of remaining command bugs have been fixed.
Made "whoosh" effect default to on, as it's a nice effect that I think most people would like. For some reason I thought I'd already done this long ago.

Also a few more bits of code improvement.