bug#46621: Copy line

[Drew Adams <drew.adams@oracle.com>]

> > Please don't give this command a default key binding.
> >
> > There are a zillion commands that deserve a default
> > binding more than this one does.  And nearly all of
> > those zillion also don't need a default binding.
> 
> There is are default bindings for transpose-lines and for
> count-lines-page.  Neither of those seems particularly useful.
> 
> Maybe there could be a prefix map for "line commands".  Something like
> ctl-x-r-map for rectangle commands.  Perhaps ctl-x-l-map.

My suggestion, if some people here are intent
on adding new default key bindings, to _not_
discuss and decide that in a bug thread.

Instead, please propose whatever you want on
emacs-devel@gnu.org.  New default key bindings
deserve discussion/review by a wider audience
than just whoever might be following some bug
thread about the introduction of a new command.

A second suggestion is that a new key binding
not be proposed at all for a new command.  In
general, at least.

Instead, wait a while, for _users_ to try the
new command and maybe bind it to different keys.
User input on their experience with commands
and keys is helpful in deciding what should
happen by default.

In general, it's not a good idea to be too eager
to add new default key bindings.  Especially
without a basis in real user experience.