"Internal mode" for rustdoc

[Manishearth]

For those writing larger software (e.g. Servo), rustdoc is a useful tool for exploring the internal methods of a crate. However, non-exported items aren't shown.

Perhaps an "internal" mode which doesn't filter out private items would be nice.

See also: http://www.reddit.com/r/rust/comments/36ce52/reflections_on_a_weekend_with_rust/crcv9kv.compact

[SimonSapin]

This looks like a duplicate of #15347 which is closed since there is a work around (--no-defaults --passes "collapse-docs" --passes "unindent-comments"). rust-lang/cargo#1520 is about making it usable in cargo doc.

[alexcrichton]

Agreed with @SimonSapin