Allow translators to change the dash symbol

[SergeyBiryukov]

In addition to curly quotes (see #10001), the dash symbol should be localized too.

wptexturize() uses – (en dash) to replace some character sequences. However in Russian — (em dash) is always used instead of that.

Is it possible to add this into 3.1?

Would we also not want to offer the em dash for translation?

We'd want $dash to be a static variable here.

Let's do this in early 3.2?

Updated the patch for both en dash and em dash.

Agreed for 3.2-early. Was just hoping :)

Refreshed for 3.3.

In [19187]:

Allow 8212/8211 (em dash and en dash) to be translated in wptexturize(). props SergeyBiryukov, fixes #15556.