Organize project files

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

harmonyqml/components/Window.qml

@@ -0,0 +1,15 @@
+import QtQuick 2.7
+import QtQuick.Controls 2.2
+
+ApplicationWindow {
+    visible: true
+    width: 640
+    height: 700
+    title: "Harmony QML"
+
+    Loader {
+        anchors.fill: parent
+        source: "UI.qml"
+        objectName: "UILoader"
+    }
+}