bug#14591: New keyword :local for defcustom

[Glenn Morris]

FWIW, seems fine to me, although defcustom + buffer-local tends not to
be terribly useful, so I don't know if it is good to advertise it more
by adding an easier way to get it?

Juanma Barranquero wrote:

> As designed, it accepts values 'local (which means make the symbol
> automatically buffer-local), 'permanent (which makes the symbol
> permanent-local), and t which does both.

t for buffer-local (most common case, I imagine) and 'permanent for
buffer-local+permanent-local seems more intuitive to me. (Do you ever
want to make something permanent-local but not buffer-local?)