Fix IRC, Fix Commands not registering, fix debug, fix some minor bugs

* Remove some SinkChat debug messages which are spamming the chat
* IrcSendMessageEvent: don't accept null targets
* SinkIRC: fix null instance
* Fix static SinkCommandOptions causing that commands are irc only
* Fix IRC not working
* Add SinkIrcReflection class
* Update SinkUser's sendDebugMessage method
* Add reloadusers to SinkDebugCommand
* Add whoami to SinkDebugCommand
* Disable SinkDebugCommand if debug is disabled
* IrcCommandSender: Fix null arguments
* Add @Unstable to Debug class, because it's sometimes showing wrong class and method calls
* Fix NullPointerException caused by StringUtil#formatArrayToString
* SinkLibrary: throw an exception if a command is available for players but not registered via bukkit