Require Gtk+ 3.10

Used for GtkHeaderBar

https://bugzilla.gnome.org/show_bug.cgi?id=709781
Implement the new deisng

* add a header bar
* remove the fullscreen mode
* remove the toolbar
* remove the face images
* uses symbolic icons

This implements the following design:
https://raw.github.com/gnome-design-team/gnome-mockups/master/games/mines/mines.png

https://bugzilla.gnome.org/show_bug.cgi?id=709781