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/chat/Root.qml

@@ -3,16 +3,23 @@ import QtQuick.Controls 2.2
 import QtQuick.Layouts 1.4
 
 ColumnLayout {
-    property var user_id: null
-    property var room: null
+    property var userId: null
+    property var roomId: null
 
+    property var roomInfo:
+        Backend.models.rooms.get(userId).getWhere("roomId", roomId)
 
-    id: chatPage
+    id: "chatPage"
     spacing: 0
     onFocusChanged: sendBox.setFocus()
 
-    RoomHeader {}
+    RoomHeader {
+        id: "roomHeader"
+        displayName: roomInfo.displayName
+        topic: roomInfo.topic
+    }
+
     MessageList {}
     TypingUsersBar {}
-    SendBox { id: sendBox }
+    SendBox { id: "sendBox" }
 }