[racket] Scribble docs from collections, feature request

The raco scribble tool is oriented around files while many of the other 
raco commands also work well with modules and collections.  I'd like to 
have the ability to, e.g., run raco scribble --lib foo/bar.scrbl where 
foo is some collection.  Currently, I have to make a file that requires 
and re-provides `doc' from foo/bar.scrbl and then scribble that.  It 
would also be nice if I could specify --style files from collections, etc.

Also, I would really like the ability to ++extra <dir> which would copy 
a directory, not just a file, into the destination directory.

Thanks,
David