Add a command like /nwl add offline

[IasonKalaitzakis]

I am transitioning from the vanilla whitelist to this plugin, and I would love a command that adds every person that has ever joined to the whitelist. Thanks :)

[NobelD]

hi, this function will be tracked in #10
there you can find a light plugin in case you want to use the function earlier
it is an add-on so it is necessary to have the base plugin
this function will be later added to the base plugin

thanks!