[atkmm] Created tag 2.53.3

[Murray Cumming <murrayc src gnome org>]

The unsigned tag '2.53.3' was created.

Tagger: Murray Cumming <murrayc murrayc com>
Date: Wed Apr 26 23:29:53 2017 +0200

    2.53.3

Changes since the last tag '2.25.2':

Chun-wei Fan (1):
      Visual Studio builds: Update glibmm ABI version

Kjell Ahlstedt (1):
      Fix build when _WRAP_ENUM generates enum class

Murray Cumming (3):
      Relation: Change RelationType to Relation::Type.
      Text: Move enums into the class.
      2.53.3