Added classes needed for private chat
Filled IPrivateChannel with content
Added SinkChat.Channels.Private.InvitedToChat.javaChat to standart localization. Added constructor to PrivateChannel.java
Fixed PrivateChannel constructor sending %p instead of correct player name.
Added needed localizations for conversations plugin.
Added methods sendMessage() addPlayer() kickPlayer() in PrivateChannel.java. Added important localizations to LanguageConfiguration.java
Added content to PrivateChannelHandler.java
Replaced class import of LanguageConfiguration by static import of _()
Improved conversations management.
Finished command handling.