v0.96: GTK3 port

New Shutter update, 0.96, is here! It drops dependency on Gtk2, and starts depending on Gtk3 instead.

More specifically, these perl dependencies are gone:

• Gtk2
• Gtk2::ImageView
• Gtk2::Unique
• Gtk2::AppIndicator
• Gnome2::Wnck
• Goo::Canvas

These dependencies are new:

• Carp:::Always
• Gtk3
• Gtk3::ImageView >= 9
• GooCanvas2 (unlike old Goo::Canvas, this one is not optional anymore)
• GooCanvas2::CairoTypes
• Pango
• libwnck-3, used via Glib Object Introspection

The feature of taking a section of window is removed (or, rather, commented out), because it didn't work with the way how modern Qt and Gtk were drawing their windows anyway.

Possible issues:

• Multiple screens might or might not be broken
• HiDPI screens might do screenshot of a nested menu in a wrong place

If you encounter these, or other issue, and/or have an idea how to fix them, please tell us.