UPDATE: split the webapp in a widget and the app itself

This splits the webapp in:

* IronCalc (the widget to be published on npmjs)
* The frontend for our "service"
* Adds "dummy code" for the backend using sqlite

webapp/app.ironcalc.com/frontend/README.md

@@ -0,0 +1,17 @@
+# IronCalc application
+
+This is the front end deployed at https:://app.ironcalc.com
+
+
+To build for production:
+
+```
+npm install
+npm run build
+```
+
+A development build:
+
+```
+npm run dev
+```