Feature Request: Display a Configurable Welcome Message to newly joined Players

[engeplabs]

Depends on #6.

I want to welcome newly joined players with a small welcome message.

[Juksuu]

This should be fairly simple to do now that #6 is implemented.

It should be done in a way where there is no message unless the corresponding setting is added to settings.txt
Also these settings could be documented in the readme once functionality is added.