Bin bin props

Florian Müllner requested to merge fmuellner/gnome-shell:bin-bin-props into master

By now, all containers and layout managers except StBin (and its subclasses) use the generic ClutterActor expand/align properties to control how their children are laid out.

This is particularly confusing as two or the properties StBin uses for layout - x-align and y-align - shadow the generic ClutterActor ones, but work very differently: They use a different enum and determine how the bin lays out its child, instead of how the bin is laid out by its parent.

Address this by deprecating the StBin properties and using the same generic ClutterActor properties as everyone else.

Continuation from !780 (merged).

Merge request reports