Now it is possible to know inside the web application when the parser failed.

- fixed the update method of code, and now actually returns the update result to the client
- now an alert is displayed when the parser couldn't parse the source, until it can finally do it again
- enhanced code and documentation of the alert method, and made possible to disable the close button
Updated documentation.

I mainly removed backlog items, aither done or moved to GitHub issues.

Some small things have been fixed too (typo, formatting, ...)

An architecture schema has been added, and you'll need to use https://www.draw.io/ to view it.