Promote shell to its own top-level directory

shell/plugins/bar/widgets/spacer.qml

@@ -0,0 +1,16 @@
+import QtQuick
+
+Item {
+  id: root
+
+  property QtObject bar: null
+  property string moduleName: "spacer"
+  property var settings: ({})
+
+  readonly property bool vertical: bar ? bar.vertical : false
+  readonly property int span: settings && settings.size !== undefined ? Number(settings.size) : 12
+
+  implicitWidth: vertical ? (bar ? bar.barSize : 28) : span
+  implicitHeight: vertical ? span : (bar ? bar.barSize : 26)
+  visible: span > 0
+}