Allow declaration of window title and documents font in index.theme

[Luca Ferretti <elle uca libero it>]

http://bugzilla.gnome.org/show_bug.cgi?id=504250  (gnome-control-center)

Basically, by now you can only define in index.theme:
	ApplicationFont
	DesktopFont
	MonospaceFont
They are used, for example, in *LargePrint themes.

The patch attached to above bug adds support to:
	DocumentsFont
	WindowtitleFont
so you can define in theme all fonts that you can manage through
Apperance->Fonts

Could someone try it and maybe lobby g-c-c maintainers? IMHO is a must
have feature for a11y themes.