LGTM, thanks!

P.S. In response to your comment of "Therefor it should not silently replace the legacy version, but should be added as a new package with "replaces" flag." - This is effectively the same as just upgrading this version. The individual isn't going to get an option during upgrade to not replace it. I think either some heads up should be given, or we should figure out a way to ship both of them as co-installable (though that'd involve considerable effort to change install paths, patch config paths, etc.).

That being said, I'd like to know what is actually incompatible. At least according to this issue, they're just using a file hierarchy and leveraging CSON in the "legacy" implementation. Was this changed in the "next" version to something which leverages a database (sqlite, indexeddb, drivers for other stuff like postgresql, etc.)?