Merge pull request #1 from EmilHernvall/master

Merge from master
Invisible admins shouldn't appear in /who
Merge pull request #2 from EmilHernvall/master

Merge from master
Added a Notification enum to easily send players notifications
Increased the volume of notifications.
Implemented a few Notifications
Notification parameter can now be null

if null, it will just send a message.
If message is null it will throw IllegalArgumentException
Fixed logic error
Merge remote-tracking branch 'sabersamus/master'
Updated /who patch to use new flags