color: Validate hex formats
color: Validate hex formats

Right now, we pass through to Pango unrecognized hexadecimal formats
when parsing colors from strings. Since we parse all possible formats
ourselves, we can do validation ourselves as well, and avoid the Pango
path.

ebassi/clutter,GNOME/clutter,Distrotech/clutter,djdeath/clutter-android,djdeath/clutter,jigpu/clutter,djdeath/clutter-android,heysion/clutter-clone,ebassi/clutter,ebassi/clutter,djdeath/clutter-android,collects/clutter,heysion/clutter-clone,Distrotech/clutter,jigpu/clutter,collects/clutter,Distrotech/clutter,collects/clutter,GNOME/clutter,jigpu/clutter,djdeath/clutter,djdeath/clutter-android,djdeath/clutter,jigpu/clutter,GNOME/clutter,djdeath/clutter-multithreaded,jigpu/clutter,Distrotech/clutter,heysion/clutter-clone,kerrickstaley/clutter-vala,GNOME/clutter,collects/clutter,djdeath/clutter,Distrotech/clutter,djdeath/clutter-android,djdeath/clutter-multithreaded,GNOME/clutter,ebassi/clutter,collects/clutter,kerrickstaley/clutter-vala,heysion/clutter-clone,djdeath/clutter-multithreaded,heysion/clutter-clone,jigpu/clutter,ebassi/clutter,djdeath/clutter-multithreaded,kerrickstaley/clutter-vala,kerrickstaley/clutter-vala,djdeath/clutter,Distrotech/clutter,djdeath/clutter