config.env if exists dpkg asks to overwrite

[Mte90]

As this file is the one used for the configuration it isn't better that is renamed as config.env.sample so who install can change it and on updated don't need to check the progress of installation and avoid an erase of the settings?

[doepke-fischernils]

abort and rename

[xylle]

in other package, there is a function which creates a new files with other extension. it's really practical