Use relative paths for files to make configuration easier

[kus]

Update Config.cs to utilise Server.GameDirectory so it's not required to hardcode the absolute paths to everything as a fallback. You can still use an absolute path, which it checks first, if that check fails it checks for a relative path so it should be backwards compatible.

This makes the plugin a lot easier to install and use across environments setup in different ways.

When I integrated your plugin into my Modded CS2 Repo all my Windows users had issues. I'm using this fix on my test Windows server and it works great now and with no modification from the default config.

Great work on the plugin by the way!