Show the Implemented Changes on Update

[Virus5600]

As of the current latest version (v1.0.x), the changes are only shown before the update. Once the update is implemented, the changes ("What's New?") are not shown. In the next update (v1.1.0), this will be implemented and will have a dedicated button in the settings/configuration screen. Changes will be saved via a file in the app (probably a separate .html or .js file) and will be parsed by frameless.js for the app to show the changelogs to the users.

[Virus5600]

Forgot to add the automatic Update changelog opener in commit 431c714. It will be added in the succeeding commits.

[Virus5600]

Needs fixing: the open-external isn't applied to its links.

[Virus5600]

As of v1.1.0-beta.4, the Changelog popup is now successfully implemented. Tested under the said pre-release.