[Development] Make qtstyleplugins an official module and release it

[Kevin Kofler]

Thiago Macieira wrote:
> So src/widgets/styles/qgtkstyle.cpp did not compile with Gtk3?

No, it doesn't. The GTK+ 3 theming API is very different.

Some Red Hat / Fedora developers have ported the Adwaita style (the default 
GNOME 3 style) to Qt natively, and that is chosen by default on GNOME 3 in 
Fedora (through a platform plugin also implemented by them: QGnomePlatform).

I do not know of any Qt style able to draw an arbitrary GTK+ 3 style, it's 
only either the old GTK+ 2 QGtkStyle or the Adwaita port.

        Kevin Kofler