bug#13032: 24.3.50; Request: Provide a `delete-duplicate-lines' command

[Dani Moncayo <dmoncayo@gmail.com>]

> Perhaps you can work from this (not very well tested):

Thank you Juanma.  I've given it a quick try and it seems to work.

I've only seen a minor detail that I don't like: when the command does
nothing (because there are no consecutive duplicate lines), the region
remains active.  But this is a general problem in Emacs which I've
already complained about (bug #10056).  IMO, the mark should be
deactivated after every command that operates on the active region,
without regard to whether the buffer was changed or not.  There could
be some exception, but this should be the general principle.

I'll put your version in my init file for now, while the maintainers
decide whether it is appropriate to add this command to Emacs or not.

Thanks.

-- 
Dani Moncayo