New optional feature: Cost to use /RTP
I've been wanting to add economy support for a while now, and I've got the most basic form in. You can now set a cost in an rtpSettings file, though it will only charge the player if they use the `/rtp` command (and not if they are teleported through `/forcertp`. This will change in the future.

How to use:
Much like the last update, if you already have your rtpSettings files you will have to add a new line like such:
Obviously you don't need the comments, but that is how it is written in the default config file. Also, if this is the first version of the plugin you download, the line will already be there.

Additional notes:
There are now four more text lines that have been added to the language file and as always you can overwrite these messages in `language-settings.yml`.