Currently, "-st-shadow" can mean one of three very
different things:
1) shadow based on alpha of the background image
2) shadow the "border box" of the node
3) shadow applied to the content of a StIcon
It isn't well defined which of the above 3 cases
-st-shadow will mean for any given node, however.
This commit splits the property into three
different properties, "box-shadow",
"-st-background-image-shadow", and "icon-shadow"
to make it all very explicit.
https://bugzilla.gnome.org/show_bug.cgi?id=636976
e727c184ef
