SkyChanger.

This release brings the following updates and changes:

• The @a paramater has been changed to -a.
• Added -w [world] parameter. This will allow you to change the sky color for everyone in a specific world. If you ommit the [world] portion your current world will be the target.
• Added new permissions skychanger.changesky.world.* and skychanger.freeze.world.*
• If you want to allow or block users from specifiying a specific world to the -w parameter, you may use the permissions skychanger.changesky.world.[WORLD NAME HERE] and skychanger.freeze.world.[WORLD NAME HERE].
• Self permissions are now included in the others, all, and world perms.
• Internal optimizations and improvements.