Some bugfixes and new features

IRC Commands:
* Add isIrcQueryOnly()  to SinkCommand
* Check if command is a query command
* MessageCommands are now only accessible via query

SinkUsers & SinkUserProviders:
* IRC Users: Send messages as private message by default
* Make SinkUser comparable
* Add getProvider() and provider variable to constructor
* Add getUserInstance(String)
* Add getCommandArgsSuffix();
* SinkLibrary: getUser(String name) does now work with commandArgSuffixes

IRC Command Handling:
* Replace source and user params from IrcCommandEvent with IrcCommandSender

Debugging:
* Add class name to debug message
* Remove some debug messages

Bug fixes:
* Fix Exception when StringUtil.format is called with ConsoleUser
* Fix SinkTabCompleter not working correctly
* Added commandArgSuffixes, this was needed because you couldn't know if e.g. a user wants to target the ingame or the irc instance of a user. The main problem is, that there may be irc users who have the same nickname like ingame. To fix that, commandArgsSuffixes has beend aded, so if you want to target an IRC user, you have to use <Name>_IRC. This is a temporary solution and may be replaced in the feature.
* Fix NullPointerException on MessageCommand if user is not online

Misc:
* Rename UserConfiguration to IngameUserConfiguration to avoid confusion, because this configuration only applies for the IngameUser class.
* Move exceptions package to api.exceptions