Add license headers to all files
Add a PrintDialog widget
Update POTFILES.in
sudoku-generator: use g_get_num_processors()

This would have been good to have known about earlier. :(
Conditionally use header bar in print multiple dialog
print-dialog: tweaks
print-dialog: workaround double emission of response signal

https://bugzilla.gnome.org/show_bug.cgi?id=737895
Workaround 100% CPU usage issue

No clue what's going wrong here....

https://bugzilla.gnome.org/show_bug.cgi?id=737507