Remove ImageItem, Paintable and use unified image provider.

js/util.js

@@ -1,12 +0,0 @@
-.pragma library
-
-function pushToStack(stack, page) {
-    if(page && stack.currentItem !== page) {
-        if(stack.depth === 1) {
-            stack.replace(page)
-        } else {
-            stack.pop(null)
-            stack.replace(page)
-        }
-    }
-}