Add tray (#2325)

* copied tray from old thread

* added visibility changer to tray

src/services/window.js

@@ -165,9 +165,15 @@ async function registerGlobalShortcuts() {
     }
 }
 
+function getMainWindow() {
+    return mainWindow;
+}
+
+
 module.exports = {
     createMainWindow,
     createSetupWindow,
     closeSetupWindow,
-    registerGlobalShortcuts
+    registerGlobalShortcuts,
+    getMainWindow
 };