[docs] Annotate properties and fix signals docs
[docs] Annotate properties and fix signals docs

Annotate the properties without gtk-doc description, to get the
"Since" attribute.

Also, fix the ::cursor-event and ::activate signals documentation.

GNOME/clutter,Distrotech/clutter,collects/clutter,heysion/clutter-clone,nobled/clutter,Distrotech/clutter,spatulasnout/clutter,collects/clutter,tardyp/clutter,heysion/clutter-clone,heysion/clutter-clone,spatulasnout/clutter,djdeath/clutter,rkudiyarov/clutter_osx,djdeath/clutter,collects/clutter,kerrickstaley/clutter-vala,spatulasnout/clutter,kerrickstaley/clutter-vala,dlespiau/clutter,spatulasnout/clutter,GNOME/clutter,nobled/clutter,ebassi/clutter,jigpu/clutter,rkudiyarov/clutter_osx,Distrotech/clutter,ebassi/clutter,djdeath/clutter,djdeath/clutter,dlespiau/clutter,rkudiyarov/clutter_osx,ebassi/clutter,jigpu/clutter,rkudiyarov/clutter_osx,heysion/clutter-clone,djdeath/clutter,collects/clutter,tardyp/clutter,djdeath/clutter-android,ebassi/clutter,GNOME/clutter,jigpu/clutter,djdeath/clutter-android,nobled/clutter,kerrickstaley/clutter-vala,kerrickstaley/clutter-vala,jigpu/clutter,GNOME/clutter,spatulasnout/clutter,Distrotech/clutter,djdeath/clutter-android,jigpu/clutter,djdeath/clutter-android,jigpu/clutter,djdeath/clutter-multithreaded,collects/clutter,djdeath/clutter-multithreaded,Distrotech/clutter,ebassi/clutter,Distrotech/clutter,heysion/clutter-clone,djdeath/clutter-android,djdeath/clutter-multithreaded,dlespiau/clutter,djdeath/clutter,GNOME/clutter,tardyp/clutter,djdeath/clutter-multithreaded