[libsigc++2] Created tag 2.3.1

[Murray Cumming <murrayc src gnome org>]

The unsigned tag '2.3.1' was created.

Tagger: Murray Cumming <murrayc murrayc com>
Date: Thu Oct 18 09:45:28 2012 +0200

    2.3.1

Changes since the last tag '2.2.11':

Kjell Ahlstedt (2):
      signal_base: Add blocked(), block(), unblock().
      Add some missing newin{}.

Murray Cumming (2):
      Update the Doxyfile.in syntax.
      2.3.1