Organize project files

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

harmonyqml/components/chat/Root.qml

@@ -0,0 +1,16 @@
+import QtQuick 2.7
+import QtQuick.Controls 2.2
+import QtQuick.Layouts 1.4
+
+ColumnLayout {
+    property var user: null
+    property var room: null
+
+    id: chatPage
+    spacing: 0
+    onFocusChanged: sendBox.setFocus()
+
+    RoomHeader {}
+    MessageList {}
+    SendBox { id: sendBox }
+}