text: Fix the default value of "editable"
text: Fix the default value of "editable"

The "editable" property is documented to default to TRUE, but is
initialized to FALSE in the _init() function.

Third party code would be affected if we changed the default to be
TRUE, so we have to change the default value in the GParamSpec.

https://bugzilla.gnome.org/show_bug.cgi?id=654726

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