Added strict type checking to the project. (#236)

* Implement strict typing (WIP).

* changes

* Finish type checks

* Fix notification icon, matugen settings and update tsconfig.

* OSD Styling updates and added the ability to configure OSD duration.

lib/types/filechooser.d.ts

@@ -0,0 +1,3 @@
+export type Config = {
+    [key: string]: string | number | boolean | object;
+}