Organize project files

Put QML components into folders, remove unused ones, split __init__.py
with engine.py.

harmonyqml/components/UI.qml

@@ -0,0 +1,39 @@
+import QtQuick.Controls 1.4 as Controls1
+import QtQuick.Controls 2.2
+import QtQuick.Layouts 1.4
+import "side_pane" as SidePane
+import "chat" as Chat
+
+//https://doc.qt.io/qt-5/qml-qtquick-controls-splitview.html
+Controls1.SplitView {
+    anchors.fill: parent
+
+    SidePane.Root {
+        Layout.minimumWidth: 36
+        width: 200
+    }
+
+    StackView {
+        function show_page(componentName) {
+            pageStack.replace(componentName + ".qml")
+        }
+        function show_room(user_obj, room_obj) {
+            pageStack.replace(
+                "chat/Root.qml", { user: user_obj, room: room_obj }
+            )
+        }
+
+        id: "pageStack"
+        initialItem: Chat.Root {
+            user: Backend.accountsModel.get(0)
+            room: Backend.roomsModel[Backend.accountsModel.get(0).user_id].get(0)
+        }
+
+        onCurrentItemChanged: currentItem.forceActiveFocus()
+
+        // Buggy
+        replaceExit: null
+        popExit: null
+        pushExit: null
+    }
+}