add an `orphans` command (fix #897)

Pretty much `nikola check -f` that outputs filenames only to stdout and
handles only “files from unknown origins”.

Signed-off-by: Chris “Kwpolska” Warrick <kwpolska@gmail.com>
Fix the `help` messages of `console` and modify ©

Signed-off-by: Chris “Kwpolska” Warrick <kwpolska@gmail.com>