Require GTK+ 3.13.2

For automatic RTL icon support

https://bugzilla.gnome.org/show_bug.cgi?id=735025
Move undo button to header bar

https://bugzilla.gnome.org/show_bug.cgi?id=735025
Layout near Iagno's and Sudoku's ones.

Based on code by Michael Catanzaro.
https://bugzilla.gnome.org/show_bug.cgi?id=735025
Prepare 3.13.90