gtk-gui: Check if the GTK version is lower than 2.24 for the about dialog

The about dialog URI calls are broken on Windows, therefore we needed
a way to override the default URI method. On versions bellow or equal to
GTK 2.24 this is possible with gtk_about_dialog_set_url_hook(),
which on the other hand is deprecated for newer GTK versions.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Update fi_FI translation

Signed-off-by: Miika Turkia <miika.turkia@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>