Added hexadecimal colors support in lang.yml and cmds.yml files.
Added an AsyncPlayerChatEvent listener that allows the use of placeholders in the chat (wich can be disabled in the config file).
Added a ServerCommandEvent and PlayerCommandPreprocessEvent listener that allows the use of placeholders in any command (wich can be disabled in the config file).
Placed YAML headers in separate .txt files, to make them easier to update.
