denial of permissions, command leakage fix, support for .txt book files

I think it's probably a good idea to tell users that they dont have
permission to use a certain command (this can be turned off, with a
later update, it will be a config) but more importantly, there must be a
return false if the user doesnt have permission so it doesnt print a
huge ammount of text.
added new command

added the command "/ls a {authors}"
this should return a list of all the authors with books theyve  written.
uses the same permission as the normal /ls (or /l or /list)