[evita] views: Utilize |common::tree::Node<T>| instead of |DoubleLinkedNode_<T>|.
[evita] views: Utilize |common::tree::descendants_or_self(Node*)| in |EditPane| to simplify code.
[evita] dom: Restructure "evita/dom/jslib/windows.js".
[evita] dom: Introduce |windows.nextWindow(current)| and |windows.previousWindow(current)|.
[evita] Fix #14: dom/commands: Make |Ctrl+Shift+0| not to lost focus.