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/base/Avatar.qml

@@ -8,7 +8,7 @@ Item {
     property var imageSource: null
     property int dimmension: 48
 
-    readonly property string resolved_name:
+    readonly property string resolvedName:
         ! name ? "?" :
         typeof(name) == "string" ? name :
         (name.value ? name.value : "?")
@@ -21,13 +21,13 @@ Item {
         id: "letterRectangle"
         anchors.fill: parent
         visible: ! invisible && imageSource === null
-        color: resolved_name === "?" ?
+        color: resolvedName === "?" ?
                Qt.hsla(0, 0, 0.22, 1) :
-               Qt.hsla(Backend.hueFromString(resolved_name), 0.22, 0.5, 1)
+               Qt.hsla(Backend.hueFromString(resolvedName), 0.22, 0.5, 1)
 
         HLabel {
             anchors.centerIn: parent
-            text: resolved_name.charAt(0)
+            text: resolvedName.charAt(0)
             color: "white"
             font.pixelSize: letterRectangle.height / 1.4
         }

harmonyqml/components/base/HToolButton.qml

@@ -14,7 +14,7 @@ ToolButton {
     onClicked: toolTip.hide()
 
     ToolTip {
-        id: "toolTip"
+        id: toolTip
         text: tooltip
         delay: Qt.styleHints.mousePressAndHoldInterval
         visible: text ? toolTipZone.containsMouse : false

harmonyqml/components/base/ToolTipLabel.qml

@@ -2,11 +2,14 @@ import QtQuick 2.7
 import QtQuick.Controls 2.0
 
 HLabel {
+    property string toolTipText: ""
+
     id: text
+
     ToolTip {
         delay: Qt.styleHints.mousePressAndHoldInterval
         visible: text ? toolTipZone.containsMouse : false
-        text: user_id
+        text: toolTipText
     }
     MouseArea {
         id: toolTipZone