Numerous warnings on startup with GTK3

[gue5t gue5t]

When running the latest git midori with GTK3, there are loads of GDK warnings printed at startup.

I tracked these down to midori_app_setup's gtk_stock_add_static calls, which are currently made before gtk_init is called. The attached patch fixes the warnings and as far as I can tell shouldn't have any ill effects; a review would be appreciated, though, as I don't know if the relative order of the gettext calls in midori_app_setup and gtk_init is important. (But as a datapoint, my locale settings were respected just fine, so maybe it's ok.)

[Cris Dywan (kalikiana)]

There's one catch you overlooked: GTK+ will eat the arguments it consumes, but we need to preserve them, for example about:version shows all arguments.

I realize that we can actually merge gtk_init into midori_app_setup and that's also fine for tests, so I went ahead and did that, while moving the argument copying upwards.

Thanks!