stage: simplify apply_transform
stage: simplify apply_transform

This simplifies the implementation of the ClutterStage apply_transform
vfunc by using the new cogl_matrix_view_2d_in_perspective utility API
which can setup up a view transform for a given perspective so that a
cross section of the view frustum at an arbitrary depth can be mapped
directly to 2D stage coordinates with (0,0) at the top left.

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