Allow access to multiple instance

[skatun]

It would be useful to have the possibility to have one account and several instances of OH(home, cabin, summerhouse etc..) and that all of them can communicate with each other and that the different sitemaps can be accessed within the same android app.

[FlorianSW]

Ok, that will be a bigger task, I'm happy to work on this, but I'm not sure, if I've enough time, and probably not enough understanding of the underlying infrastructure, yet, however, I hope I can get help, if I need it. But, I think we can't do this in one commit only and it will take some time to do all needed changes :)

[Gozilla01]

Hello, I'm very interested in this improvement. Are there any news?

[electraport]

Recently discovered this project and fans of open source. Took a fork and looking into it. Will do our best to contribute back.