Start rewriting backend with pyotherside+asyncio

src/qml/EventHandlers/includes.js

@@ -0,0 +1,2 @@
+// FIXME: Obsolete method, but need Qt 5.12+ for standard JS modules import
+Qt.include("system.js")

src/qml/EventHandlers/system.js

@@ -0,0 +1,8 @@
+function onAppExitRequested(exit_code) {
+    Qt.exit(exit_code)
+}
+
+function onCoroutineDone(uuid, result) {
+    py.pendingCoroutines[uuid](result)
+    delete pendingCoroutines[uuid]
+}