The old behavior of quoting `like this' doesn't look good with

The old behavior of quoting `like this' doesn't look good with
newer, ISO-style fonts.  See:
http://www.cl.cam.ac.uk/~mgk25/ucs/quotes.html

Instead, quote "like this" by default.  Let the translator
tailor the locale-specific quoting behavior by providing
translations for {LEFT QUOTATION MARK} and {RIGHT QUOTATION MARK}.

(N_): New macro.
(gettext_default): New function.
(quotearg_buffer_restyled): Use
gettext_default ("{LEFT QUOTATION MARK}", "\"") for left quote, and
gettext_default ("{RIGHT QUOTATION MARK}", "\"") for right quote.