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/MessageList.qml

@@ -14,8 +14,7 @@ Rectangle {
         id: messageListView
         anchors.fill: parent
         delegate: MessageDelegate {}
-        model: Backend.models.roomEvents.get(chatPage.room.room_id)
-        //highlight: Rectangle {color: "lightsteelblue"; radius: 5}
+        model: Backend.models.roomEvents.get(chatPage.roomId)
 
         clip: true
         topMargin: space
@@ -31,7 +30,7 @@ Rectangle {
 
         onYPosChanged: {
             if (yPos <= 0.1) {
-                Backend.loadPastEvents(chatPage.room.room_id)
+                Backend.loadPastEvents(chatPage.roomId)
             }
         }
     }