Capitalization, list model and room header work

- Standardized capitalization for variables and file names everywhere in
  QML and JS, get rid of mixed camelCase/snakeCase,
  use camelCase like everywhere in Qt

- ListModel items are now stored and returned as real QObjects with
  PyQt properties and signals.
  This makes dynamic property binding a lot easier and eliminates the need
  for many hacks.

- New update(), updateOrAppendWhere() methods and roles property
  for ListModel

- RoomHeader now properly updates when the room title or topic changes

- Add Backend.pdb(), to make it easier to start the debugger from QML

harmonyqml/components/UI.qml

@@ -1,7 +1,8 @@
+import QtQuick 2.7
 import QtQuick.Controls 1.4 as Controls1
 import QtQuick.Controls 2.2
 import QtQuick.Layouts 1.4
-import "side_pane" as SidePane
+import "sidePane" as SidePane
 import "chat" as Chat
 
 //https://doc.qt.io/qt-5/qml-qtquick-controls-splitview.html
@@ -14,12 +15,9 @@ Controls1.SplitView {
     }
 
     StackView {
-        function show_page(componentName) {
-            pageStack.replace(componentName + ".qml")
-        }
-        function show_room(user_id, room_obj) {
+        function showRoom(userId, roomId) {
             pageStack.replace(
-                "chat/Root.qml", { user_id: user_id, room: room_obj }
+                "chat/Root.qml", { userId: userId, roomId: roomId }
             )
             console.log("replaced")
         }
@@ -28,6 +26,12 @@ Controls1.SplitView {
 
         onCurrentItemChanged: currentItem.forceActiveFocus()
 
+        initialItem: MouseArea {  // TODO: (test, remove)
+            onClicked: pageStack.showRoom(
+                "@test_mary:matrix.org", "!VDSsFIzQnXARSCVNxS:matrix.org"
+            )
+        }
+
         // Buggy
         replaceExit: null
         popExit: null