EFA#139 Support efa Online Update via Github

[cubitusgh2]

New efa software packages will be made available on GitHub in the future: https://github.com/nicmichael/efa/releases

For future online updates, efa will allow updates to be performed via this repository.

Users will be able to choose between production releases and pre-releases.

Users will be able to select a newer version from a list, and the changes compared to the current version will be displayed.

Beta versions will be clearly identifiable, and the notices from eou.xml will also be displayed.